From The Stargate Omnipedia
An Altairan android, friend of Harlan. Wallas was the last to survive along with Harlan under the surface of Altair, long after the world had been destroyed. Many robotic duplicates had survived in the factories, but one-by-one they eventually decided to end their lives. Wallas was the last to end his existence, leaving Harlan to fend for himself.
Tin Man - Harlan speaks fondly of Wallace while explaining the history of his planet to SG-1.