Harvey Pekar was 70. His "American Splendor" comics, which he began publishing in 1976, chronicled his grousing about work, money and the monotony of life.
Here's his classic appearance on Letterman from 1988 when he got banned from the show.
And if you haven't yet seen American Splendor, the 2003 biopic starring Paul Giamatti as Harvey Pekar, you're missing out. It's fantastic.