Jean Porter in Cry Danger (1951).
Buster Keaton with, yes, Boris Karloff in makeup as Frankenstein's Monster at a charity baseball game in Los Angeles, 1940. Buster typically led the comedians' team at the games, held to benefit Mount Sinai Hospital. He'd show up with his gag men, a truck of props, and plenty of routines all worked out to make the event as successful as possible for its good cause. (Scanned from Gone But Not Forgotten, 1981.)
Color footage of Hollywood in 1931, processed with Cinecolor, from the travelogue short "Round About Hollywood."
Ann Savage and Tom Neal in Edgar G. Ulmer's Detour (1945).