Just a few:
Jean Tissier
http://filmsdefrance.com/FDF_jtissier.html
He invariably played the slow-talking guy who liked to invites himself (a freeloader). Wether in comedies of crime films, he is a hoot!
Saturnin Fabre
http://filmsdefrance.com/FDF_Saturnin_Fabre.html
He plays often very excentric old men in a completely mad fashion. I start laughing each time I see him on the screen.
Noël Roquevert
http://filmsdefrance.com/FDF_Noel_Roquevert.html
His usual casting is stuffy old army officer, sometimes scary and mysterious.
Bernard Blier
http://filmsdefrance.com/FDF_bernardblier.html
He is certainly more than just a 'character actor', but at the beginning of his career he always played the guy whose wife cheats on him. He is just a wonderful supporting character.
Jules Berry
http://filmsdefrance.com/FDF_jberry.html
Always smartly dressed, a good talker, and also a dangerous man. He always looks like an envoy of the devil. He is the one who makes Gabin a murderer in Daybreak. He is really a wonderful ham!