Spiderman co-creator Steve Ditko has died at age 90:

New York police confirmed to The Hollywood Reporter on Friday that one of Marvel Comics’ legendary staffers, Steve Ditko, was found dead in his apartment this week. Ditko was 90.

The creator of Dr. Strange and the original artist (plus “co-creator,” according to Stan Lee) for Spider-Man had been found days earlier, on June 29, and police told THR that they believed he had been dead for two days when he was found. Reports indicate Ditko left behind no family or survivors.

Ditko’s impact on Marvel Comics may only be rivaled by his reclusive nature in later years. After creating and developing Spider-Man with Lee in 1961, Ditko premiered lasting hero Dr. Strange in 1963, and Ditko would continue to write and draw Dr. Strange stories for Marvel until 1966. Disputes over money and friction with Lee reportedly drove Ditko to leave Marvel in 1966, and Ditko shunned the public spotlight shortly thereafter; he gave his last formal interview in 1968, though he continued contributing comics to other publishers.

Most notably in his later career, he created Squirrel Girl.