Memento is a 2000 American neo-noir psychological thriller film written and directed by Christopher Nolan, adapted from his younger brother Jonathan's short storey "Memento Mori".

Memento is presented as two different sequences of scenes: a series in black-and-white that are shown chronologically, and a series of colour sequences shown in reverse order. The two sequences "meet" at the end of the film, producing one common story. It stars Guy Pearce as Leonard Shelby, a man with anterograde amnesia, which impairs his ability to store new explicit memories, who has developed a system for recollection using hand-written notes, tattoos, and Polaroid photos. During the opening credits, which portray the end of the story, it is shown that Leonard kills Teddy (Joe Pantoliano). The film suggests that this killing is vengeance for the rape and murder of his wife (Jorja Fox) based on information provided by Natalie (Carrie-Anne Moss).

Memento premiered on September 5, 2000, at the Venice International Film Festival to critical acclaim and received a similar response when it was released in European theatres starting in October 2000. Critics especially praised its unique, nonlinear narrative structure and themes of memory, perception, grief, self-deception, and revenge. The film was successful at the box office and received numerous accolades, including Academy Award nominations for Original Screenplay and Film Editing. The film subsequently was named as one of the best films of the 2000s decade by several media outlets.