Leonard "Leo" Francis Dooley (played by Tyrel Jackson Williams) is the protagonist of the Disney XD series Lab Rats. He was sent plummeting into a secret underground lab in the basement of the home he shares with his inventor stepfather, Donald Davenport, his mother, Tasha, and Eddy, the "smart house" computer, where he discovers three teen super-humans, who he first thinks make danger, but it turns out they end up being his best friends.
Leo is a normal teenager who finds the bionic trio in his new dad's place. Leo is not popular at school, and he only wishes to be a great inventor like his dad and be finally be known.Leo is the only character in the show to wear long sleeves.
Crush, Chop and Burn"
Despite the episode's title being "Leo's Jam," Leo does not appear very often as a main character.
At the beginning of the episode, Leo tries to ask Danielle to the dance in order to teach Adam and Chase how to ask a girl out to the dance. After his unsuccessful attempt, Bree arrives and begins to moan about the dance. He is not seen again until he, Adam, and Chase escape from Ethan.
He appears again when he and Adam are fighting with toy robots. Chase arrives with a plan to make Danielle like Leo. They devise a plan that they are sure will work. At school, they place a row of lockers on top of Adam to make him appear to be trapped. When Danielle and her friend see Adam under the lockers, Leo announces that he will save Adam. Since Leo cannot lift the lockers on his own, Adam helps him by pushing upwards on the lockers. In doing this, Danielle falls in love with Adam and not with Leo.
When at the lab, the boys try to talk it out, but Leo gets angry and jumps on Adam, screaming. Eventually, Adam reluctantly agrees to let Leo go to the dance with Danielle.
The next day at school, when Leo, Adam, and Chase all meet up with Bree, she believes that she had scared Ethan off, and Leo reminds her about the skid marks she left in the hallway.
Leo is seen again when Chase announces that he is going to the dance with Danielle, Leo jumps onto Chase and begins to scream, like he did to Adam.
Leo and Adam are both mad at Chase for going to the dance with Danielle. When Chase tries to explain what happened, Adam asks Chase if he’s taking Danielle to the dance after all. When Chase says that he is, Adam becomes angry and storms away.
Leo gives up his dreams of having Danielle as his girlfriend, and says that if he can’t have Danielle, then he’s glad Chase can have her. He then asks if Chase knows how to dance, and teaches him the “Refrigerator Dance.”
At the dance, Leo is seen when Bree arrives in high heels. He suggests that she wear a helmet with them because she is stumbling so much.
After this, Leo is not seen until he comes out to dance with his aunt and her book club. His dance causes Danielle to dance with him for the rest of the dance, until he realizes that Adam and Chase’s feelings are hurt.
He leaves Danielle to apologize to Adam and Chase. Together, they promise to never let a girl come between them “At least not until tomorrow,” they add as a girl walks by. They jump up and chase after her.
"Rats on a Train"
He is first seen when Davenport announces to the Lab Rats about their extreme climate training. When he complains that he wants to be "abused by weather." It is then revealed that he receives brain freezes from chewing mint gum, thus proposing that he could have sensitive teeth.
"Exoskeleton vs. Grandma"
Donald Davenport is Leo's stepfather. He created the bionic trio and owns the house that Leo moves into.
Tasha Davenport is Leo's mother.
Rose Dooley is Leo's grandmother.
- Bionic Arm: Leo received this bionic arm after Taylor crushed him in You Posted What?!?. This was his first time recieving Bionics other than Parallel Universe.
- Laser Sphere Generation: In You Posted What?!?, according to Douglas, Leo can generate laser energy and form them into laser spheres from his fingers and shoot them from his hand. This is also Leo's main bionic ability as being the one he uses the most. It is also strong enough to knock out Krane and they can set things on fire. The laser bolts can knock out powerful bionic humans, such as Taylor, or even Krane as stated above, or blast objects to pieces or blast aside metal.
- EMP Generation: Leo discovered a brand new bionic ability where he can combine laser spheres with another bionic person (usually Taylor) to generate an EMP to knock out any electrical equipment.
- Super Strength: Just like his big brother Adam, Leo's arm is shown to have superhuman strength, allowing him to be strong enough to crush Perry's hand and making it become swollen. And in Armed and Dangerous, Leo uses his bionic strength to lift up the couch with one hand without visible strain in a similar manner to how Adam lifted it one-handedly. Also, like Adam, he was not visibly discomforted by the weight of the couch and balanced it well in his hand. In Bionic Rebellion, Leo used his super strength to throw Tank out of the window. However, some metals take him a while to break with his arm.
- Energy Transference: This is one of Leo hidden abilities until Rise of the Secret Soldiers. Douglas unlocks this ability for him to fight the bionic army. This ability can absorb any type of energy source and it can be used medically (though this is highly discouraged due to the life-risks). Leo defeated Taylor for the first time with this ability. While Leo used the ability to heal Donald, it's not clear if it can be used to bring a dead person back to life. He can also absorb kinetic energy, which was how Leo was able to catch the falling space elevator.
- Super Durability: Leo bionic leg and arm are both pretty durabile after he receive bionics
- Bionic Leg: In Space Elevator, Donald gives Leo's left leg bionics because it was broken by the elevator, and he was afraid he couldn't go any missions. The only known capabilities include super strength as shown when Leo kicked the basketball a great distance using his leg and when it bounced back, it knocked Donald down. In The Vanishing, his leg was shown to be even stronger then his bionic arm, being able to tear through a steel wall, something his bionic arm only put a small dent in.
- Leo says that his middle name is Danger, even though it's really Francis. He says it is pronounced Danger but spelled F-R-A-N-C-I-S.
- He has a crush on Danielle.
- Leo is considered a nerd until he meets Bree, Chase, and Adam.
- Leo's mother mentioned that his teachers think he is strange.
- Leo is not very good at basketball.
- Leo is a good dancer.
- He wants to be like the Lab Rats.
- Leo gets brain freezes just from chewing mint gum, which could possibly mean he has sensitive teeth.
- When Leo looks for his room, he says that he needs a GPS "just to find the bathroom".
- Douglas gives Leo a bionic arm, since it was so injured by Krane and S1 he could not use his normal arm.