Doctor Strange

Doctor Strange on Ebay
Doctor Strange 1970's #1-81 plus one Annual, June 1974 - February 1987.

After the character's initial outing as a continuation of his run in Strange Tales, Marvel took a chance on the Sorcerer Supreme character in the mid-70's to give him his own series and, probably to much surprise, it was a decent success, lasting over twelve years. (His appearance in The Defenders might have helped.)

Doctor Strange was never one of the company's top-tier characters, but he was interesting enough - and the nature of his abilities and general milieu were interesting enough - to sustain his popularity to some degree. But the good Doctor (despite such vehicles as the recent feature film) always seemed to work better as a support character.