Quoted from Newsarama
"According to several sources, legendary X-Men and comic book artist Dave Cockrum passed away in his sleep last night, his death a result of diabetes and its resultant complications. He was 63 years old.
Cockrum, a fixture of the American Comics scene in the ‘70s was born in Oregon to a father who was a lieutenant colonel in the US Air Force. As a result, Cockrum traveled frequently as a child, which allowed comic books to provide some semblance of stability from city to city.
Following his father into the military, Cockrum served in the Navy for six years following high school, and then entered comics and publishing, first at Warren Publishing, and then as an assistant inker to Murphy Anderson at DC Comics. It was during this period that Cockrum’s art became known with the Legion of Super-Heroes, helping them to move from their Silver Age roots into a more modern look.
While his Legion work is widely known to Legion fans, Cockrum will forever be known as the artist who, with Len Wein, and later with Chris Claremont, created the new X-Men, and redefined both the existing characters and revitalized the world of the mutants and the franchise for Marvel. Cockrum had two major stints as artist on Uncanny X-Men, from Giant-Size X-Men #1 in 1975 through 1977, and then from 1981-1983.
Though he had worked less and less in comics in recent years, Cockrum had never left the hearts of his fans, as they rallied around him when it was announced in 2004 that he was seriously ill due to complications from diabetes and pneumonia. A benefit book and action was held, while Marvel Comics announced that it would pay Cockrum retroactively for his work in design and co-creation of the new X-Men. "