In superhero comics, no one stays dead except Jason Todd and Bucky Barnes. Oh wait, they've come back by now too. Ben Parker remains the only that has so far stayed dead.
Comic Book Death have also expanded into other fandoms, such as Doctor Who, Xena, Charmed, Star Trek, and InuYasha.
A prime example for a Comic Book Death would be Jean Grey. She never stays dead... not for long anyway.
Other comic book examples: Barry Allen ("died" in 1985, 2008 he returned), Steve Rogers ("died" in 2007 and returned in 2009), Magik.
In Doctor Who, Rory Williams dies multiple of times. Jack Harkness could also hold this title as he's died more than 1,000 times (although this is due to Bad Wolf accidentally turning him into an immortal).
In Charmed, each of the Halliwell sisters (Prue (3 times), Piper (12 times), Phoebe (9 times), and Paige (9 times)) have all died several times, with Prue Halliwell the only one remained dead.
Buffy Summers from Buffy the Vampire Slayer is a prime example from that series.