The Flintstones #4

Hanna-Barbera's prehistoric pals collide with the future in this 1978 Marvel release, as the cover shows Fred Flintstone and Barney Rubble looking bewildered by a panicked, ray-gun-toting George Jetson crying "Help!" — with a stone-club-wielding prehistoric cop looming close behind. The film-strip border running down the left side spotlights a lively parade of other beloved Hanna-Barbera characters, giving the whole cover a fun, crossover-celebration feel. Cover art by Roger Armstrong and Joe Prince sets the playful tone for the interior tale teased as "Stone Age Spaceman," written by Mark Evanier with art by Roger Armstrong.