Lily Potter
Background
Lily Potter was a witch. She was married to James Potter and her son is Harry Potter. Lily was killed by Voldemort while defending Harry. She was a member of the Order of the Phoenix.
During the events of Harry Potter and the Sorcerer's Stone (2001) played by Geraldine Somerville
Hagrid tells Harry the story of Voldemort and how Harry's parents stood up to Voldemort, but were eventually killed by him.
During the events of Harry Potter and the Prisoner of Azkaban (2004) played by Geraldine Somerville
Harry Potter is sitting in his room practicing spells when Uncle Vernon walks in and checks on Harry. After After using magic on Aunt Marge, Harry runs to his room and looks at the moving photo of James and Lily.
During the events of Harry Potter and the Goblet of Fire (2005) played by Geraldine Somerville
At the Riddle family cemetery, Voldemort challenges Harry to a duel and as they are dueling, their wands appear to cancel each other out. The dead spirits of Frank Bryce, Cedric Diggory, James and Lily appear and James tells Harry to run to the Goblet, which acts as a Portkey.
During the events of Harry Potter and the Order of the Phoenix (2007) played by Geraldine Somerville
Harry looks at his photo of James and Lily and then remembers the murder of Cedric at the hands of Voldemort. Harry goes to leave for Hogwarts, but before he does, Sirius Black gives him a photo of the original Order of the Phoenix, which included Neville Longbottom's parents.
During the events of Harry Potter and the Half-Blood Prince (2009) played by Geraldine Somerville
Professor Horace Slughorn shows Harry a photo he has of his former students, including one with Lily. In Hagrid's hut, Slughorn tells the story of his pet Francis who was given to him by Lily Potter.