Doom lives large on the cover of X-MEN #145, which was the first monthly issue of X-MEN that I ever bought, back in 1981. Why? Because I’d seen them in an issue of ROM and they seemed like interesting characters, fresh and not stodgy like the DC characters of the time. Understand that I wasn’t really reading monthly comics by then, just licensed stuff like MICRONAUTS and ROM, which was my gateway to the expanded Marvel universe.
Of course, I’d known about Dr. Doom from my copy of BRING ON THE BAD GUYS, which I still have to this day (and cost me the unimaginable sum of twelve bucks in 1977 or so). I was always puzzled why the Marvel comics on the stands then didn’t square up with what I’d seen in those books from the likes of Kirby, Buscema, Romita and Ditko.
Note the visible crease from it being folded into a back pocket so I could carry it back and ride home from the convenience store.
1981, Marvel Comics
Dave Cockrum and Joe Rubenstein cover