<Li> Katherine Helmond as Mona Robinson </Li> <P> Delta Burke appeared in the first season as next door neighbor, Diane Wilmington . Comic James Coco was a frequent guest, beginning in season one as Tony's father - in - law, visiting from New York, Nick Milano . People have credited his appearances on Who's the Boss? as a prime example of his comedic abilities on TV, despite the fact that he was not a regular and had never starred in a successful TV series of his own . When Coco died in February 1987, prior to the conclusion of season three, his character was written out as having died as well (with a funeral episode and tribute). </P> <P> By the fall of 1990, with Samantha beginning college and Jonathan in high school, Who's the Boss?, like other series getting on in years, added a new younger cast member . Producers brought in five - year - old Billy (Jonathan Halyalkar), a kid from the Micellis' old Brooklyn neighborhood, whose grandmother left Billy in Tony's care . He moved in with the Bower family in season 7 . Billy was a comic foil to Tony, but also attempted to get into the mix in other characters' storylines . He only lasted that season, however . In the E! True Hollywood Story about the series, Katherine Helmond remarked that Halyalkar was a gifted performer, but had difficulty catching up to the pace of the acting and timing the senior cast members had long established with each other . He was written out of the show at the end of the season . In the beginning of season 8, it was briefly explained that Billy had gone to live with another foster family . </P> <P> Frank Sinatra made a guest appearance in a 1989 episode, as well as Ray Charles, Mike Tyson and Thomas Hearns . Betty White also made a guest appearance in the first season as a local TV director . Leslie Nielsen played Max, who was engaged to Mona in a 1988 episode . Matthew Perry played Benjamin Dawson, a roommate of Samantha's in a 1990 episode . </P>

Who played billy on who's the boss