Martin Landau (1928-2017)
With well over 100 credits to his name no one can say that Martin Landau didn't have a fine and enduring career. But for such a fantastic talent, perhaps he remained undersung. After a brief stint as a cartoonist, he found his calling with acting and nabbed his first TV guest spots in the mid '50s. By the end of the decade he appeared in his first classic (Alfred Hitchcock's North by Northwest) but it wouldn't be his last. For the remainder of his long long career he toggled between TV (most notably three seasons in the mix of Mission Impossible in the 60s and leading the cult favorite Space 1999 in the 70s) and intermittent movie success.
You can't call it his late 80s/early 90s success a comeback, given that he never quit working, but it was a revival and a rediscovery...