Leon Scott Kennedy makes his first appearance as one of the two protagonists in Resident Evil 2. Leon is a recently-hired police officer for the Raccoon Police Department. He arrives late to Raccoon City and finds the town already overrun by zombies. He works with Claire Redfield and attempts to escape the city alive. He is partnered with Ada Wong, a woman claiming to be looking for her missing boyfriend. His attempt to find an escape route leads him to Umbrella's underground laboratory, where he confronts several of Umbrella's mutant creatures.
The epilogues of Resident Evil 3 reveals that Leon made an undisclosed deal with a representative of the US government for Sherry's safety. In Resident Evil: Survivor and Code: Veronica Leon has joined an anti-Umbrella force. In Survivor, he is the one who sent the game's protagonist, Ark Thompson, to Sheena Island. In Code: Veronica, Claire gets in touch with Leon when she is trapped on Rockfort Island, and Leon relays her whereabouts to Chris Redfield. Leon also appears in Resident Evil: Gaiden.
Leon returns as the protagonist of Resident Evil 4. He has become a special agent for the US government, and is assigned to rescue the newly-elected President's daughter, Ashley Graham, who is being held somewhere in Europe. Her kidnappers turn out to be part of a cult known as Los Illuminados, which has taken control of the local villagers with parasites known as Las Plagas. Leon teams up once again with Ada Wong, and Luis Sera, a former researcher for Osmund Saddler, the cult leader.