Family
- father Mario Baio:
- cousin Jimmy Baio: Acted in the TV series "Soap"
- cousin Joey Baio: Acted in the series "The Hero"
- daughter : Born Nov. 2, 2007; mother, Renee Sloan
- mother Rose Baio:
- brother Steven Baio: Older; twin of Stephanie
- sister Stephanie Baio: Older; twin of Steven
Companions
- Companion Erin Moran: Met on the set of "Happy Days"; also starred together on "Joanie Loves Chachi"
- Beverly D'Angelo: born in 1954; dated briefly; broke up over age difference
- Heather Locklear: dated from 1984 to 1986
- Jeanette Ulrika Jonsson: born c. 1975; attending UCLA; together since 1999
- Lesley Ann Warren: linked romantically after being introduced by Warren's son, Chris Peters
- Nicole Eggert: co-star on "Charles in Charge"; dated during the run of the series
- Nicolette Sheridan: dated in the late 1980s
- Pamela Anderson: starred in the TV series "Baywatch"; dated in 1989; engaged to be married; separated; reunited briefly in 1993
- wife Renee Sloan: Married Dec. 8, 2007 in Los Angeles, CA; mother of his daughter
