Android 18 is a fictional character in the Dragon Ball manga series created by Akira Toriyama. Android 18 makes her debut in Chapter #349 "The Androids Awake!", first published in Weekly Shōnen Jump on November 12, 1991.
She and her twin brother, Android 17, were forcibly turned into cyborgs by Dr. Gero to serve his vendetta against Goku. The main-timeline version of the character has very little to no interest in fulfilling Gero's orders and becomes a major character in the series after marrying Goku's best friend Krillin.
In an alternate future timeline, Android 18 is a ruthless killer who started a reign of terror along with Android 17 over Earth that lasted for twenty years until they are both killed by adult Trunks.