(Covers information from Anderson's universe)
"I didn't lose this many friends so that you could just walk away. "
— To Alice.
During Alice's captivity, Leon's team, comprised of Barry Burton, Luther West, and two others (Sergei and Tony), entered the underwater Umbrella facility in Russia where Alice was being held captive with the intention to destroy it should their rescue mission fail.
Leon and his team planted bombs on the surface and interior of the facility. The bombs were set to go off in two hours and destroy the facility, regardless if the team or Alice has escaped the facility. The plan was to rendezvous with Ada Wong in the suburban Raccoon City simulation of the facility and head back to the surface. However, upon entering Moscow simulation, they were met with heavy resistance from the Undead roaming the facsimile of Red Square.
The team was pinned down, thrown off schedule and practically overpowered by their enemy when they're rescued by Alice in a Rolls Royce. During their escape, Alice inquires why Leon is helping Wesker and Leon says that he isn't working for Wesker.
Returning to the elevator, Leon and the others prepared to leave but were held back by the attacking Umbrella soldiers. Barry was injured by the Licker who ambushed them prior in Moscow and when Alice chose to go and save Becky (who'd been captured by the Licker), Leon objected to the idea, citing that to waste what time they had left would result in a mission failure. He ultimately backed down and joined Barry and Luther in the effort to hold the soldiers back. Eventually, the injured Barry opted to remain behind and sacrificed himself so that Leon and Luther can escape.
Leon and Luther eventually reunite with Alice and Becky and escape the base as it was destroyed. During their departure, they are cut off by Jill and Rain, who caught up to them in one of the destroyed base's submarines. As they prepared to fight, Rain injected herself with a virus and Leon recognizes the vial she uses as the "Las Plagas parasite".
Leon and Luther West engaged in a two-on-one fight with Rain while Alice fought Jill, but Rain proved to be more than a match for them. She broke the arm of Leon and killed Luther with a single blow to the chest. Rain defeats Leon easily, tossing him against the side of the submarine before engaging in battle with Alice.
After Rain is killed, the group is rescued by Wesker from the frozen tundra and taken to Washington, D.C. where the former head of Umbrella filled Alice in on their situation against the Red Queen's army of Undead.
Little information is provided on Leon's background during the events of Retribution. According to Johann Urb, Leon and Barry are friends akin to "partners in crime". Ada and Leon also appear to share a past history together, Leon's confidence in her strong is enough that he implicitly trusts her to survive or escape any situation she lands in.
In The Final Chapter, Wesker's aid of Leon's team and Alice is revealed to be a deception to draw the remnants of humanity into one location so that he can destroy them. Leon and everyone at the White House except Wesker himself and Alice were killed in the betrayal.
In the official novelization of Resident Evil: The Final Chapter, it is revealed that Leon S. Kennedy was consumed by a creature exclusive to the novel, the Melange, that absorbed him into its mass, killing him.
Skills and abilities
Leon is an incredible marksman, capable of making head shots from over fifty yards and rarely missing his intended target as well as showing a proficiency with fully automatic weapons. It can be assumed that Leon is skilled in knife combat, trying to use it on "Bad Rain." His overall fighting skills shined when they were put to the test when Rain engaged Leon in a fight in which Leon was able to hold his own. Leon was able to match Luther in hand-to-hand combat evenly until they both were beaten by Rain.
Appearance and wardrobe
Leon wears a charcoal grey T-shirt with a high neck. It looks suspiciously like rubber, or wetsuit material. There are many seams running down the sides, sleeves and back. He wears navy blue combat pants over black laced boots/shoes. Leon also wears a tough tan leather jacket lined with sheepskin. On Leon's right leg he wears a holster with two straps. This is attached to a webbed belt with storage pouches. He wears a brown leather shoulder holster which crosses at his back. This holster also houses his knife in a sheath on his left shoulder. He wears black fingerless gloves and carries a handgun. His hair is light brown and cut long and floppy, with a side partings.
- For Resident Evil: Apocalypse, Screen Gems created a promotional faux newspaper, "The Raccoon City Times", that detailed the background of Jill Valentine, and also included that she was dismissed from the S.T.A.R.S. after the death of her partner, Leon Kennedy .
- The following is an excerpt from "The Raccoon City Times" that is accessible through a link above:
During yesterday's press conference, Captain Hendersen noted that Officer Valentine had been suffering from post-traumatic stress disorder due to the recent death of her partner, Leon Kennedy. "Jill Valentine is one of our most gifted and intelligent police officers, but she just needs a good rest right now," said Captain Henderson. "She made wild accusations of monsters living in the Arklay Mountains. I think this leave of absence will give her time to clear her head," Captain Henderson continued.
- Paul W. S. Anderson wanted Jensen Ackles to play Leon three times for Resident Evil: Extinction, Resident Evil: Afterlife and Resident Evil: Retribution.
- Matthew Mercer who voiced Leon S. Kenndey from the games and the voice used for the audition's reference audio, tried out for the role and didn't get it. He still finds the situation hilarious to this day.
- The team considered redubbing Johann Urb's voice as Leon due to his Finnish accent.