Beginning in the late fifties, Roy Lichtenstein became famous for what some later called "pop art" paintings, many of which were enlarged comic book panels. Over at this site, a gent named David Barsalou displays some of the results of a long-term research project, which was to find the original source material for Lichtenstein's paintings. Most of them appear to me to be panels by John Romita, Russ Heath, Mike Sekowsky and Jerry Grandenetti. Needless to say, Mr. Lichtenstein made a lot more money off his versions than the real artists did from creating the originals.
As far as I know, there is no record of Roy Lichtenstein actually drawing comic books even though he was traipsing about New York from around 1951 to 1957 looking for commercial art jobs. Jack Kirby claimed that Lichtenstein applied for work at the Simon-Kirby studio during this period but that his samples weren't good enough. I'm not sure I believe that but it's at least possible.