Gunslinger Girl (stylized in all caps) is a Japanese manga series written and illustrated by Yu Aida. It was serialized in Dengeki Daioh magazine from May 2002 to September 2012. Its chapters were collected in 15 tankōbon volumes by ASCII Media Works. Set in modern Italy, the series focuses on young cybernetic girls and their adult male handlers who use them as assassins under the directions of a government organization.

The manga series is licensed for an English language release in North America by Seven Seas Entertainment. A thirteen-episode anime adaptation produced by Madhouse aired in Japan on Fuji Television from October 2003, to February 2004. A sequel titled Gunslinger Girl -Il Teatrino- and created by Artland premiered in Japan on Tokyo MX TV in January 2008. It spanned thirteen episodes, concluding in April 2008. Two additional episodes were released on DVD in Japan in October 2008. Funimation has licensed both anime seasons and the OVAs.

As of December 2012, Gunslinger Girl had over 3.9 million copies in circulation. In 2012, the manga won the Excellence Award in the Manga Division at the 16th Japan Media Arts Festival.