- Along with his sisters, performed in their family's song-and-dance troupe, the Daniels Family, in New York.
- In his teens, he debuted on Broadway in Life With Father.
- Portrayed John Adams in the Broadway version of 1776 and reprised the role in the 1972 film.
- Worked hard to lose his Brooklyn accent, adopting an accent closer to that of his Boston-based character from the NBC medical drama St. Elsewhere.
- Won an Emmy in 1986 along with wife Bonnie Bartlett for St. Elsewhere, on which they portrayed Dr. and Mrs. Mark Craig. The couple also played husband and wife on the ABC sitcom Boy Meets World and the CBS drama Touched by an Angel.
- Elected president of the Screen Actors Guild in 1999, upsetting incumbent Richard Masur.
- Northwestern created the Willies—an annual awards ceremony for excellence in theater at his alma mater—in his name.
- The original voice of the talking car in NBC's Knight Rider, he reprised the voice of KITT for recordings on a Knight Rider GPS system created by Mio Technology.
- 1983, Emmy — Outstanding Lead Actor in a Drama Series: Nominee
- 1984, Emmy — Outstanding Lead Actor in a Drama Series: Nominee
- 1985, Emmy — Outstanding Lead Actor in a Drama Series: Winner
- 1986, Emmy — Outstanding Lead Actor in a Drama Series: Winner
- 1987, Emmy — Outstanding Lead Actor in a Drama Series: Nominee
- David Daniels — Father
- Robert Daniels — Son
- Michael Daniels — Son
- Irene Daniels — Mother
- Bonnie Bartlett — Wife
- Northwestern University, Evanston, IL (1949, BA in Theater)
Season 2, Episode 4
- Birth Place: Brooklyn, NY
- Birthday: March 31, 1927, Aries
- Profession: Actor, Voice-overs