Milestone birthday for “Boy Meets World” star William Daniels … he’s just made it 99 trips around the sun!!!

William, who famously played Mr. George Feeny on the hit 1990s sitcom, celebrated his 99th birthday Tuesday in Los Angeles … marking the occasion by going to Art’s Deli with his wife, actress Bonnie Bartlett.

William and Bonnie have been married almost 75 years, a major accomplishment especially in Hollywood, and lunch at Art’s Deli has become a birthday tradition for old Bill here.

While an entire generation remembers William for starring role on “Boy Meets World,” he’s also known for his work on St. Elsewhere … on the 1980s TV series, he played Dr. Mark Craig … and in 1967’s “The Graduate,” he plays Dustin Hoffman’s dad, even though Dustin is only 11 years younger.