Who do you mean? Do you mean Pompey (who was independently killed by Egyptians), Cato (killed himself rather than be pardoned), Ahenobarbus (was defeated, tried to kill himself, then was pardoned by Caesar only to fight again and be defeated again and killed in battle), Labienus (defeated, pardoned, killed in battle), Cicero (defected to the Pompeiians and was actively solicited by Caesar to return to public service, never punished by Caesar), Petreius and Juba (fought a suicidal dual with a slave killing the victor). Whom else am I missing? I'm curious as to whom you mean.

Or do you mean the very alive and formerly Pompeiian Senators that Caesar enriched and restored to office that ultimately killed him out of pride?