what were they before? Hanna Barbara?
I thought they were always looney tunes characters.
Sorry to WELL ACKSHUALLY this, but they were MGM characters created by the two dudes who went on to found Hanna Barbera. Same as Droopy, Spike the Bulldog, The Wolf and Screwy Squirrel.
MGM sold their animation division to Ted Turner, who also bought Hanna-Barbera. Turner then sold his cartoon rights holdings to Time Warner. Warner has almost always kept these various characters in their own universes, but they've technically been under the same roof since the early 90's.