Sif

Sif is a friend of Thor's and The Warriors Three. She first appeared in Thor and appeared again in Thor: The Dark World. She is portrayed by Jaimie Alexander.

Thor: The Dark World
"I had things under control!"

- Sif

''Sif is one of Asgard's most formidable warriors. Skilled and fearless, she's a trusted and faithful ally to Thor. During his banishment, Sif saw Loki's treachery and risked all to return Thor to Asgard…but on Earth, she saw that she had lost Thor's heart to another—the human Jane Foster. Now at the end of a long campaign to free the Nine Realms from strife, Sif seeks to rekindle her relationship with Thor.''

The Avengers: Earth's Mightiest Heroes
Sif is a young woman who was hails from Asgard. There, she grew up alongside Loki, Thor, and Amora the Enchantress.

She was seen leading the Valkyries alongside Brunhilde against a trio of Frost Giants who had besieged both Giant Man and an unconscious Wasp. Sif assisted in several battles during war against Loki, but was defeated. She was later present when Odin took his place on the throne, and cheered for the Avengers alongside her fellow Asgardians.

While Thor stayed in Asgard, Sif overheard how Thor missed Jane Foster, a mortal from Midgard. She interrupted them remarking Thor that he should return to Midgard. Thor went away after Odin arrived and reported that Surtur was missing from Muspelheim and the Warriors Three reported that something was troubling Heimdall, so Thor went to find out the cause.

She was present when Odin summoned Beta Ray Bill who was holding oned Beta R. She attacked without hesitation the Korbonite, but was easily defeated. He was then taken hold by Odin and summoned Thor. Bill explained his backstory and Sif offered to help him to save his people from the Fire Demons and offered her sword after Odin rejected the proposal of Thor giving Mjolnir to him and suggested that they have Eitri, a dwarf, make a hammer for Bill.

After Bill acquired the hammer Stormbreaker, they went to the Skuttlebutt, currently being attacked by the Fire Demons. While Thor and Bill battled the demons, she went into the ship and activated the system of the Skuttlebutt, and ordered the ship to go after the Enchantress who was commanding the Fire Demon army, but was stopped by the ambush of more demons. She went to the place of the sleeping pods where the Korbonites rested and fended off the Fire Demons, until they vanished after Thor and Bill defeated the Enchantress. After they arrived at the Skuttlebutt, she offered to Bill to protect the Korbonites, but Bill refused since he thought her duties lied elsewhere. She bade farewell to Bill and left with Thor apologizing to him for earlier.