This wasn't a "comics series" per se, but a character called "Yankee Doodle" was originally slated to appear in SHOWCASE #50 (1964) but didn't.
It wasn't until DOOM PATROL (second series) #51 in 1992 that Yankee Doodle made his actual first appearance in print in a story by Grant Morrison as well as a cover by the original artist/co-creator of Yankee Doodle, Mike Sekowsky.
More info here:
http://members.tripod.com/originalvigilante/yankeedoodle.htm
