Friends and Allies
Like all Jedi, Obi-Wan deeply respected Yoda and was trained by him as a young boy; prior to Obi-Wan becoming Qui-Gon Jinn's apprentice. He obeyed Yoda usually without question.
After Obi-Wan died, he entrusted Luke's training to Yoda.
Like most Jedi, Obi-Wan held Mace in high esteem for his mastery of Form VII. Mace also held Obi-Wan in high esteem for his mastery of Form III. However, despite their mutual respect for each other, Obi-Wan often disagreed with Mace's questionable decisions. This was due to the fact Obi-Wan was a moderate who followed the Jedi Code and Mace was an extremist with a secret emotional attachment to the Galactic Republic.
Obi-Wan had a strong bond and friendship with his mentor Qui-Gon Jinn, whom he held in high esteem. However, they often clashed due to philosophical differences; Obi-Wan was a more devoted follower of the Jedi Code and proponent of the Unifying Force. Qui-Gon, on the other hand, preferred to follow his conscience and the will of the Living Force. When Darth Maul killed Qui-Gon, Obi-Wan was devastated and vowed to pick up where his mentor left off.
After Anakin turned to the Dark Side and became Darth Vader, Qui-Gon's spirit taught Obi-Wan the technique of retaining his identity through the Force (something Qui-Gon had himself learned from the Force Priestesses), a technique that enabled him to become a Force spirit after death.
Obi-Wan first met Padmé shortly after the Invasion of Naboo started, when he and his mentor Qui-Gon rescued her from the Trade Federation's battle droids. They did not have much interaction with each other. However, throughout the Clone Wars, the two became close friends.
At some point, during the Clone Wars, Obi-Wan came to (secretly) suspect that Padmé and Anakin were having an affair, however, he was only partly (correct) as unknown to him, the two latters' were in fact married, but he never revealed his suspicions that the Jedi council; proving just how loyal he truly was to Padmé. When Obi-Wan discovered that Padmé was pregnant, he quickly figured out that Anakin was the father of her unborn child, unknown to him (at the time) Padmé was in fact pregnant with twins.
In Revenge of the Sith, their friendship became strained after Anakin told her of Obi-Wan's apparent intent to use him as a spy for his own purposes. Padme did not believe Obi-Wan when he told her of husband's dark deeds, mainly because she was in denial and partly because of what Anakin told her. To reassure herself that what he had said was not true, she traveled to Mustafar to ask Anakin herself; unknown to Padmé, Obi-Wan had stowed away on her Naboo star skiff, so he could find Vader and and kill him.
This proved to be fatal for Amidala as Anakin thought that she had betrayed him and force choked her to unconcinciousness, making her lose her will to life. Obi-Wan was furious and horrified upon seeing such an act and, immediately demanded that Anakin let Padme go, displaying that despite Padme's initial refusal to believe him, the strain put on their friendship by Anakin was on Padme's part and not Obi-Wan's and, he still cared deeply for her as a friend.
After defeating and leaving Vader for dead, Obi-Wan immediately did everything he could to save her and provide her comfort, even lying that he had not killed Vader despite by that time believing Vader is most likely dead and reminding of her children and that they need her but all of Obi-Wan's attempts was futile and she died despite this.
Obi-Wan was saddened by her death, it's safe to assume he feels guilt, shame and remorse for her death, as he technically was who made Vader kill her. Obi-Wan also displayed his respect of Padme by not telling Luke about Padme when he asked about his mother, knowing that Padme would not want her son to known the true extent of the tragic relationship between Vader and her.
Before her death, Padmé told Obi-Wan that there is still good left in Anakin and that one day he can be redeemed. However, though Obi-Wan was just as heartbroken as she was about Anakin's transformation, he could not bring himself to believe her.
Obi-Wan first met Ahsoka during the Battle of Christophis. At first, Obi-Wan thought Ahsoka was going to be his apprentice until Ahsoka revealed that she was assigned to be Anakin's apprentice. Later, Obi-Wan told Anakin off for being so harsh with her and told him to cut her some slack. Over the years, Obi-Wan's trust in her grew.
When Ahsoka was accused of treason, Obi-Wan was one of the extreme few that were doubtful she had committed the crimes. When Wilhuff Tarkin demanded that Ahsoka be expelled from the Jedi Order and turned over to the Republic military courts, Obi-Wan tried to convince his fellow Council members to refuse and stand by Ahsoka, due to seeing that there was no real proof of her so-called treason. Unfortunately, Obi-Wan was out-voted, and Ahsoka was cast out of the Jedi Order. Although Obi-Wan didn't agree with the Council's decision, he did nothing to help clear Ahsoka's name. When Barriss Offee was exposed as the true culprit, Obi-Wan didn't seem surprised that Ahsoka was innocent and was saddened when she left the Jedi Order for good.
But Obi-Wan refused to truly acknowledge that the council were at least partly responsible for Ahsoka leaving the Jedi Order in the first place (incorrectly) believing that Ahsoka had let emotion cloud her judgment, something against the Jedi way; proving that he refused to see the members of the Jedi Council's flaws and unjustified actions, even when there was evidence to prove so.
Hondo held Obi-Wan, along with Anakin and Dooku hostage. But after they freed themselves, they left Hondo's base with no intention for revenge, which Hondo respected. Three years later after Darth Maul returned, Hondo helped Obi-Wan fight Maul and his brother Savage Opress. Hondo seemed to respect Obi-Wan greatly.
After Luke was born, Obi-Wan took him to Tatooine, to be raised by his father's step-brother Owen Lars, and his wife Beru Whitesun, in order to protect him from Palpatine. Obi-Wan watched over him for nineteen years. Before discovering Obi Wan's true identity, Luke believing him to be a strange hermit, under the name of "Ben Kenobi".
Upon the arrival of R2-D2 and C-3PO, Luke learned of Obi-Wan's former identity and life as a Jedi. After this knowledge, he gained great respect and admiration for the Jedi Master. During their journey to Alderaan, the two quickly became good friends. On the first Death Star, Obi-Wan was killed by Darth Vader while attempting to escape. Luke was devastated by the death of his mentor, but continued to fight in in the Galactic Civil War, so that Obi-Wan's death would not be in vain.
When he discovered that Vader was his father, Luke became angry that Obi-Wan had lied to him, but eventually forgave him.
Obi-Wan first met Owen when he came to Tatooine with the infant Luke Skywalker, tasking Owen, along with his wife Beru, to protect Luke, Obi-Wan lied about Anakin Skywalker's circumstances (as the latter had turned to the Dark side, betraying the Jedi Order and adopting the persona of Darth Vader) instead said that he had died in the Clone Wars. Devastated by his step-brother's supposed death, Owen blamed Obi-Wan for what had happened to Anakin, believing he had brainwashed the latter into joining the Jedi Order and had failed to protect him.
Owen also felt that Obi-Wan was personally responsible for the deaths of Shmi and Anakin and, that the Jedi Master's actions torn his family apart.
Since then, Owen had been cold and hostile towards the Jedi Master, as the latter was never welcome at his homestead and, Owen forbade him from visiting - fearing that Obi-Wan would get Luke killed as Anakin (apparently) was - the relationship between the two never improved; even prior to Owen's death.
Obi-Wan first met Beru when he came to Tatooine with an infant Luke Skywalker, tasking Beru, along with her husband, Owen, to protect Luke, with the lie that Anakin Skywalker had been killed in the Clone Wars.
Unlike Owen, Beru was never hostile or cold towards the Jedi Master and, after Obi-Wan saved Luke's life from a Krayt Dragon - Beru felt grateful towards the latter for saving her nephew's life. Beru quietly disliked when Owen raved against Luke's Jedi protector, but did not stop him.
Kanan had a Jedi Holocron that contained Obi-Wan's message; regarding the fall of the the Republic and that the surviving Jedi must go into hiding until the time was right for them to come out of exile, it is unknown if the two had met or knew each other. Like many of the surviving Jedi, Kanan believed Obi-Wan was killed in the Jedi Purge (due to the fact that the surviving Jedi were unable to contact each other, as they have gone into hiding).
In "Visions and Voices", Ezra Bridger learned via a Nightsister ritual, that the means to defeat the Sith was "Obi-Wan Kenobi". Kanan was surprised to find out that Obi-Wan was still alive and referred to him as "Master Kenobi", implying that Kanan only knew the latter via his reputation.
When Ezra was briefly the Galactic Empire's prisoner, he opened Kanan Jarrus' Jedi Holocron that contained Obi-Wan's message; regarding the fall of the Republic and that the surviving Jedi should go into hiding until the time was right for them to come out of exile. Ezra had not yet meet Obi-Wan at the time, it is unknown if he had learned via Kanan about the latter's reputation and status. In "Visions and Voices", Ezra learned through a Nightsister ritual, that the means to defeat the Sith lay with "Obi-Wan Kenobi".
Obi-Wan somehow knew of Ezra as well, before meeting him and, upon being told of Maul hunting him by the younger Jedi, Obi-Wan stated to him that Maul was not Ezra's responsibility and that he should return to where he was needed most. Ezra eventually did as Obi-Wan said, displaying that despite their brief meeting, he respected Obi-Wan greatly.
Obi-Wan and Maul had been enemies since the Invasion of Naboo. When Maul killed Qui-Gon Jinn, Obi-Wan picked up when he left off and defeated him. Unknown to Obi-Wan, Maul survived the injuries Obi-Wan had inflicted and after several attempts to obtain revenge against the Jedi Master decades later eventually killed Obi-Wan's love interest, Satine Kryze, to cause him pain. When Maul tracked Obi-Wan to Tatooine, they dueled one last time, with Maul falling to Obi-Wan's blade once and for all. Although Maul and Obi-Wan had been enemies for the longest time, and despite the fact that he was responsible for the deaths of Qui-Gon and Satine respectively, Obi-Wan held no hate for his enemy after killing him, and closed his foe's eyes when he died out of respect.
Obi-Wan initially respected Dooku for training his beloved mentor Qui-Gon. This came to an end after seeing with his own eyes that he had become a Sith Lord. He later learned from the Pikes Syndicate that he was the man called Tyranus that Jango Fett told him about and realized that his Sith name is Darth Tyranus.
Unlike most people such as Anakin, Obi-Wan was unimpressed with Palpatine and was the first person who saw what he really was due to seeing him as another politician. When Dooku revealed to him the existence of Darth Sidious and that the Dark Lord of the Sith had hundreds of Senators under his control, Obi-Wan didn't believe a word of it, stating the Jedi would've sensed it. However, as the Clone War dragged on, Obi-Wan began to suspect that Dooku was telling the truth.
After the Invasion of Coruscant, Mace Windu revealed that Darth Sidious was traced to 500 Republica, the residence of the officials of the Republic Government. Obi-Wan realized that Dooku was indeed telling the truth and later warned Anakin to be careful around Palpatine. After the Execution of Order 66 and the Declaration of a New Order, Obi-Wan learned that the now Emperor Palpatine and Darth Sidious were one and the same. Obi-Wan would live the rest of his life with the horror that the Jedi Order had been too blind to stop Palpatine before it was too late.
When Obi-Wan first met Anakin, he (apparently) didn't think much of him due to how young he was despite having seen how high his midi-chlorian count was, whereas the Jedi Council was against Anakin's training due to his age and internal conflict, Obi-Wan's reason for opposing it was mainly because he was (secretly) jealous of him, after Qui-Gon was killed, he took Anakin in as his apprentice to fulfill his mentor's dying wish, he often clashed with Anakin for his frequent disobedience, as well as his impulsive and prideful attitude. However, Obi-Wan (secretly) always defended Anakin at every turn and always found a way to make Anakin's mistakes his own. He was also the first to insist that Anakin be made a Jedi Knight.
At some point, during the Clone Wars, Obi-Wan came to (secretly) suspect that Anakin and Padmé Amidala were having an affair, however, he was only partly (correct) as unknown to him, the two latters' were in fact married, but he never revealed his suspicions that the Jedi council; proving just how loyal he truly was to Anakin. When Obi-Wan discovered that Padmé was pregnant, he quickly figured out that Anakin was the father of her unborn child, unknown to him (at the time) Padmé was in fact pregnant with twins.
When Anakin turned to the Dark side and became Darth Vader, Obi-Wan was heartbroken and only resolved to fight Vader because Yoda ordered him to do it, during their duel on Mustafar, Obi-Wan kept trying find a trace of his former apprentice in the monster he had become, but it was in vain and he eventually accepted that Anakin was (apparently) gone. After Obi-Wan dismembered Vader and won the duel, he could not bring himself to murder his defenseless enemy in cold blood, and remorsefully left Vader to be consumed by the flames of Mustafar.
Obi-Wan later took Luke to Tatooine to keep him safe and later learned during a Holonet broadcast of the Subjugation of Kashyyyk that Vader was still alive and had been rebuilt as a cyborg; Obi-Wan was shocked and horrified, mainly because Vader was still alive, but also because of what his actions had resulted in his former friend becoming a cyborg; due to Obi-Wan not killing him when he had the chance to put Vader out of his misery.
Nineteen years later, Obi-Wan told Luke that Vader betrayed and murdered Anakin, which was true from a certain point of view, not long afterwards, Obi-Wan re-encountered Vader once more on board the first Death Star, Vader engaged his former mentor in a final lightsaber duel, expressing contempt for him due to his advanced age. However, even after years apart, both lightsaber duelists felt grief over their shattered friendship, but this did not prevent them from using the full extent of their lightsaber skills. When Obi-Wan left himself wide open, Vader cut him down, not knowing it was a ploy to distract Vader from capturing Luke Skywalker and his companions.
Even as a Force spirit, Obi-Wan continue to believe that Vader was irredeemable and, there was no good left in him, however, this was disproved when Vader's son, Luke, was being tortured by Palpatine and, Vader broke away from the Dark side, becoming the good person he once was; proving that Obi-Wan was wrong and that anyone had the chance to redeem themselves from the Dark side.
It is unknown, but likely that Obi-Wan feels ashamed not only for never believing in Anakin's inner goodness, but also for being a lousy friend to the latter.
Obi-Wan and Tarkin work together very well during the Clone Wars. However, unlike Anakin Skywalker, Tarkin appeared to have virtually no respect for Obi-Wan.
Despite the fact he fought alongside Obi-Wan in the Clone Wars, Tarkin arrogantly underestimated his former ally, believing the latter was killed in the Jedi Purge.