The best piece of advice Ray Sumser received before graduating from art school was to make something he would want to own.

“So I tried to make a picture that was all of my favorite cartoon characters,” said the artist, who grew up in Sausalito. “That then grew into as many cartoon characters as I could think of in one picture.”

His work since then has largely revolved around large-scale paintings featuring literally thousands of recognizable pop-culture characters. You might see Ralph Wiggum from “The Simpsons” rubbing elbows with the Stay-Puft Marshmallow Man from “Ghostbusters” and the dragon from “The NeverEnding Story,” but stand back far enough and they’re all subsumed into an eye-popping blotch of color.

“I started doing this when I was young, where I would do mashups of different characters,” Sumser said. “I wrote a whole comic book about Sonic the Hedgehog racing the Road Runner.”

Sumser, who lives in San Francisco but works out of a studio in San Rafael, is about to turn 40. He’s celebrating his birthday with a retrospective of his career from 7 to 10 p.m. March 21 at GCS Agency at 201 Jackson St. in San Francisco.

The event is free. RSVPs through Eventbrite get a free print at the show.

In addition to showing his large-scale cartoon pieces, he’ll also be debuting an animation project, “High Magic,” about the countercultural escapades of a party-loving wizard called into action when his friend is kidnapped by trolls.

“It’s all really irreverent comedy,” he said. “It’s not all family-friendly, but it’s my own.”

He’s also releasing an album of original songs at the event, which he describes as being in the vein of ‘90s comedy rockers like They Might Be Giants and the Presidents of the United States of America. Titled “buildsong,” the project was recorded in under a month, with Sumser playing all the instruments including electronic beats programmed with Ableton Live software.

“The real goal was to have vinyl printed, so I’ll get to actually have vinyl for sale at the show,” he said. “It’s 16 tracks of pretty silly but also vulnerable music.”

Sumser’s work can feel like a sugar high when taken in all together, but it’s easy to detect a resistance to being pigeonholed as the pop-culture cartoon guy. Over Zoom, he shows off a piece called “Cosm:R” that’s based on a drawing he made in 2014, which he finalized in 2020. The characters therein seem familiar at first but are slightly skewed, with one prominent figure resembling the Statue of Liberty with an eye patch and a scowl. Others are like mirror-world versions of the Grinch or Bugs Bunny.

“In 2014, I was really in the prime of doing these big cartoon-universe pictures, and, by 2016, I’d actually really burned out on that type of work,” Sumser said. “It started to feel like it wasn’t my own thing. At some point what I’m really giving people is their connection to something that already exists.”

In 2016, Sumser began focusing on the kind of idyllic landscapes one might more readily expect from a Marin painter, all blue skies and golden-green slopes. The one problem: he was living in New York City at the time.

“I find that with art, it’s helpful for people to have a useful reference point,” Sumser said. “It’s possible to do a painting of Mount Tamalpais or Marin that people get really excited about. It’s harder to make paintings of Mt. Tam when you’re living in Manhattan and people are wondering what landscape it is.”

The challenge of selling an audience on new material rather than playing the hits is a familiar one to many artists. Sumser recalls a Van Morrison performance he attended, which consisted entirely of new songs except for a lifeless version of “Brown Eyed Girl” the famously cantankerous singer — and one-time Marin resident — tacked on at the end.

“You get known for one thing, and you have to do that thing because people want it,” Sumser said. “But I’ve continued to develop. I’m still growing. It’s a tough balance.”

The fruits of this growth will be on full display at Sumser’s upcoming retrospective, which he sees not just as an exhibition but as an opportunity to reconnect with the people who helped him on his journey along the way.

“I get to invite my high school drama teacher, my mock trial coach and my favorite English teacher,” said Sumser, who went to Tamalpais High School. “I’m really excited to have new people come and see the work, but the impetus was really to share the work with people who have supported me since I was a kid doing little drawings.”