Project A-ko (Japanese: プロジェクトA子, Hepburn: Purojekuto Ēko) is a 1986 Japanese animated science fiction action comedy film. The film focuses on 16-year-old Japanese teenage schoolgirl A-ko, who defends her best friend C-ko, as they face off against their classmate and rival B-ko while the Earth faces the threat of an alien invasion. It was directed by Katsuhiko Nishijima with Yuji Moriyama did animation direction and character design. The film project initially started as part of the Cream Lemon series of original video animation, but later became its own film. The film staff said they were motivated to produce a fun exciting film in contrast to the more serious anime films being produced at the time. Additionally, the film includes a variety of references and parodies a number of other works of anime from the 1970s and 1980s.

The film was largely well received by critics who praised the humor and action and considered it an anime classic. Outside of Japan, the film was seen by many fans of anime which served as an introduction to the medium. The film was followed up by several sequels and a spin-off, starting with Project A-Ko 2 in 1987. The original 35mm film negatives were once thought lost until they were recovered in 2021.