Robin Williams and Marsha Garces Williams, married in April 1989, are splitting up. Garces Williams filed a divorce petition in San Francisco on March 21, seeking to end her marriage to Williams on the grounds of irreconcilable differences.

She is in her early 50s; he is 56. They married soon after Williams' divorce from Valerie Velardi, to whom he had been married for 10 years. Williams' and Garces' daughter, Zelda, was born in July of that year; their son, Cody, in 1991.

Williams and Garces met while she worked as a nanny for Zachary, born in 1983 to Williams and Velardi. Garces subsequently worked as personal assistant to the comedian. Four years after their marriage, in a New York Times interview, he said, "I don't need to go out to a club now and get a little bit of intimacy from 100 or 200 people. Now I can get that talking to friends around the table."

Over the years, as their family grew, Williams and Garces worked together, both professionally and toward values they shared. In 1991, they founded Blue Wolf Productions; Garces produced "Mrs. Doubtfire," "Patch Adams," "Jakob the Liar" and "Robin Williams Live on Broadway."

Together they also created the Windfall Foundation, a non-profit that focuses on education, health, the environment and the arts. Garces has particularly been involved with Doctors Without Borders and Seacology; Williams with the Christopher Reeve Foundation (he was Reeve's classmate at Juilliard) and Comic Relief. Their house, in Sea Cliff, was the site of a variety of big-ticket fundraising dinners and cocktail parties, but also Halloween central for neighborhood trick-or-treaters.

Williams has done two publicly acknowledged stints in rehab: for drugs in the '80s and, after staying sober for 20 years, for alcohol in 2006. The couple was out and about at various events upon his return, and in the past year, he has delighted Bay Area audiences by dropping in unannounced for surprise appearances at comedy events and clubs.

Garces was not at Williams' side when he was honored by the San Francisco International Film Festival last spring, and amid reports of many sightings in Marin County, where he was said to have been living, rumors of problems have been rife for months.

Garces' lawyer, Robert Kaufman of Beverly Hills, would provide no information.