Android 17 was created by Dr. Gero. Android 17 was a runaway with his sister, Android 18. But he was captured by the Red Ribbon Army and put in a chamber and turned into an android. Android 17 woke up and destroys Dr. Gero. He fought the Z-Fighters with his sister. He was absorbed by Imperfect cell. In Kid Buu, he was still alive and was giving his energy to Goku.
In GT, Android 17 is fused with Hell's Android 17 to form Super Android 17.