Jill Valentine is a fictional character in the Resident Evil horror franchise by Capcom. The character, widely regarded as one of the most attractive women in video games, gained great popularity and was met with generally very favorable critical reception.
Jill made her debut appearance in 1996 as one of the protagonists of the original Resident Evil game, in which she is a member of the U.S. special police force STARS trapped in a mysterious mansion. During the later events of Resident Evil 3: Nemesis, Resident Evil: The Umbrella Chronicles, Resident Evil 5 and Resident Evil: Revelations, Jill escapes from a city overrun by zombies and becomes a founding member and field operative of the UN-funded paramilitary group BSAA.
Like most women in a zombie apocalypse, today's cosplayer decides to strip out of her clothes and get naked... makes sense to me. Enjoy.