“Simpsons” fans — and animal lovers — across the Twittersphere are bidding farewell to the show’s co-creator Sam Simon, who passed away this weekend after a hard-fought battle with colorectal cancer. He was just 59.

More from Variety:

In 1989 he developed “The Simpsons” with Matt Groening and James L. Brooks, and he subsequently co-wrote nearly a dozen “Simpsons” episodes during his tenure on the animated comedy, also serving as co-showrunner, character designer, creative consultant, creative supervisor, developer, and writer. He left the show in 1993 while retaining an exec producer title.

The animated sitcom, he said, gave him more freedom than live action. “You can draw animals and sets but the animated characters also have freedom. The Simpsons sometimes do things that real people wouldn’t do.”

But Simon was also a devoted philanthropist. An animal lover, he funded the Sam Simon Foundation, which rescued dogs, funded a traveling animal surgery clinic assisting the ailing pets of those who otherwise could not afford medical attention for them and provided vegan food for hungry humans. He also supported PETA, which named its Norfolk, Va., HQ the Sam Simon Center; Save the Children; and global marine conservation organization the Sea Shepherd Conservation Society, which named one of its vessels after him.

RIP.

Thoughts and prayers to Simon’s loved ones.

Editor’s note: This post has been updated with additional tweets.