Her role in Resident Evil: Apocalypse
Sienna was reported to have studied the original character's movements by watching playthroughs of the video game Resident Evil 3: Nemesis. Before getting the script for the film, she had not been familiar with the video games or seen Resident Evil.
She said about her role: You always want to play someone you’re going to have fun with, someone you want to be. Jill’s got everything a girl wants to be – she dresses to kill, says whatever she wants and can shoot anyone between the eyes in a fifty-yard radius. She’s hard as nails and she’s great fun. And not at all afraid of being quite the sexy minx.
Sienna's costume was taken directly from the game and limited her movement in the martial arts sequences, leading the fight choreographers to give her more punching and gun play.
Resident Evil: Extinction
She was asked to reprise in Resident Evil: Extinction but didn't accept due to scheduling conflicts with Eragon.
She appeared in the 2006 fantasy film Eragon with Resident Evil: Extinction actor Chris Egan.
Resident Evil: Afterlife
Sienna Guillory briefly reprised her role as Jill Valentine in a post-credits scene.
Resident Evil: Retribution
Sienna Guillory reprised her role as Jill Valentine in the film Resident Evil: Retribution