Robert A. Silverman is a Canadian actor cast five times by writer/director David Cronenberg. He is sometimes credited as Bob Silverman or Robert Silverman. Wikipedia
Naked Lunch
Hans
eXistenZ
D'Arcy Nader
Scanners
Benjamin Pierce
Waterworld
Hydroholic
The Brood
Jan Hartog
Rabid
Man in Hospital
Prom Night
Mr. Sykes
Winter Kept Us Warm