Tough question.  I suppose looking up the dates would help, but among the earliest I can recall...


THE WONDERFUL WORLD OF THE BROTHERS GRIMM
SANTA CLAUS CONQUERS THE MARTIANS
DARBY O'GILL AND THE LITTLE PEOPLE
IN SEARCH OF THE CASTAWAYS


It's tough to be sure about some of the older Disney cartoon features, because in the early-60's they actually used to run them on their TV show!  In later years, they stopped that, realizing they'd have an easier time forcing people into theatres if they DIDN'T run them on TV.

For example, I know I saw Disney's ALICE IN WONDERLAND on TV in the early 60's, and didn't see it in an theatre until the late 70's.  I distinctly recall seeing CINDERELLA at a drive-in, but it seems to me I saw both SNOW WHITE and BAMBI on TV years before seeing them in theatres.

SANTA CLAUS CONQUERS THE MARTIANS I saw in the same theatre 2 years in a row!