Android 15

Android 15 (人造人間１５号, Jinzōningen Jū Go) is Dr. Gero's fifteenth creation. He was designed to serve Gero's vendetta against Goku, who overthrew the Red Ribbon Army as a child. He made his debut in the 1992 film Super Android

In the original concept art drawn by Akira Toriyama, Android 15 is labeled as Android 14 and Android 14 is labeled as Android 15, but the anime staff switched their names around due to the story development and other circumstances.

In the Dragon Ball manga and the Androids Saga of Dragon Ball Z, Android 18 asserts that Dr. Gero destroyed the first fifteen androids he designed, however this disturbs the canonicity of both the mainstream series (as Android 8 makes cameo appearances throughout both Z and Dragon Ball GT) and Super Android 13!, which features androids 13, 14 and 15 as its lead villains. Super Android 13! provides an original explanation that while Dr. Gero was murdered by Android 17 prior to personally completing 13 through 15, he leaved an underground supercomputer to finish the models posthumously.

Even though Android 13, 14, and 15 were not featured in the manga, the "Androids A-B-C's" section mentions that Androids 13, 14, and 15 were very close to the Android concept.


Information from:
http://dragonball.wikia.com/