If he had still been alive today, Jack Kirby would be 96 years old.
It always breaks my heart that his name isn't a household name along with Stan Lee. Along with Steve Ditko, Kirby co-designed the Marvel Universe as we know it. With Joe Simon, he co-created Captain America. Then, with Stan Lee, he co-created the Fantastic Four (and all characters familiar with their mythos, including The Inhumans, Namor, Galactus, Silver Sufer, Doctor Doom, etc), The Avengers, The X-Men (before they were later popularized by Chris Claremont), Thor, and a slew of others under each of those titles.
On top of that, he created some very memorable characters over at DC, including Etrigan the Demon, Kamandi, OMAC, The Challengers of the Unknown, and of course most famously The Fourth World, which gave us Darkseid, arguably one of the greatest super-villains in comics (certainly in the top 5).
And yet he never gets the same credit as Stan Lee, because Lee was a very charismatic spokesperson; the "voice" of the Marvel Universe, if you will. Lee spread himself so thin with so many projects that, in fact, the artists would do most of the work, creating the comic in full and then Lee would add in his own dialogue. Not to belittle Lee's work in the business because he does deserve it, but it bugs me that he always gets full credit by nearly everyone outside of the business.