Weiss was one of the intelligent holograms created by Hirogen engineer Donik to serve as prey for their holographic training simulations. He was modelled after a Human Starfleet officer. He was later liberated by Iden and became part of his rebellion.
Weiss was one of the more aggressive members of Iden's rebellion. (VOY: "Flesh and Blood")
The holographic Weiss may have been created from a template of Lieutenant Weiss, an officer stationed aboard USS Voyager, although this was never substantiated.
His name comes from the script.