Was a professional pilot for a year in the early 1980s.

Was invited to join the Academy of Motion Picture Arts and Sciences (AMPAS) in June 2004.

Children: Son Gill Williams (b. 1992) and daughter Elinor Williams (b. 1998).

Certified Flight Instructor, rated in single and multi-engine airplanes and helicopters.

Graduated from Franklin & Marshall College in 1973

Graduated from Kent School, the same high school that Ted Danson, Peter Farrelly and Seth MacFarlane attended.

Andy Brown, Williams' character on "Everwood" (2002), was ranked #43 in TV Guide's list of the "50 Greatest TV Dads of All Time" [20 June 2004 issue].

Had a brief romance with Dana Delany.

In 2003, completed two weeks of training to qualify for flying jet engine planes.

The nickname "Treat" comes from one of his maternal ancestors, Robert Treat Paine, whose signature appears on the Declaration of Independence.