Trivia

In an episode of Incorrigible Cory (1993), Daniels's character, George Feeny, is congratulating Cory on the quality of his film project. Cory then asks, "You think it's a great film?" George responds, "No, I think The Graduate is a great film," referring to his earlier role in Le lauréat (1967).

One episode of Hôpital St. Elsewhere (1982) called for Dr. and Mrs. Craig to visit Philadelphia. Inspired by returning to Independence Square, he sang a few lines of the song "Sit Down, John" from 1776 (1972). The moment was included in the episode.

Portrayed John Adams in the original Broadway stage version of 1776 and reprised his role in the movie 1776 (1972).

He recorded his lines as K.I.T.T. in K 2000 (1982) on his days off from Hôpital St. Elsewhere (1982).

As a child, he was part of the Daniels Family song-and-dance troupe that traveled in and around the state of New York. His entire family appeared on one of the first experimental TV broadcasts in 1941.

While performing on both Hôpital St. Elsewhere (1982) and K 2000 (1982) in the 1980s, Daniels made goodwill visits to children's hospitals. He discovered that not many children were thrilled to meet an actor who played a doctor, but the fact that he voiced the talking car KITT always appealed to them, so he shifted emphasis during his visits. He entertained the children with KITT-styled phrases, and answered their questions about "Knight Rider" while hardly mentioning his other, larger acting role.

Due to his popularity on Hôpital St. Elsewhere (1982), Daniels was also invited to speak at medical school graduations, esp. at Northwestern, his Alma Mater. He turned each and every one of them down, because he wasn't a doctor, in real-life.

Played Dustin Hoffman's father in Le lauréat (1967), but in reality is only 10 years older than Hoffman.

Played George Feeny, who was the principal and a teacher at John Adams High School on the TV show Incorrigible Cory (1993). This is yet another John Adams connection for Daniels, who has portrayed him many times.

Has known Ed Begley Jr.'s family, when he was very young, years before he co-starred on Hôpital St. Elsewhere (1982) with him.

Often plays members of the famous Adams family of early American history. Has played John Adams (in the feature film 1776 (1972), the television mini-series The Rebels (1979), and the original play of "1776" on Broadway beginning in March 1969) and his son John Quincy Adams (in the television mini-series La famille Adams (1976)).as well as their cousin Samuel Adams (in the television mini-series The Bastard (1978)).

The characters that Daniels and his real-life wife, Bonnie Bartlett, played in Incorrigible Cory (1993) married each other in an episode of that series, just as they are in real life.

Prior to starring on Hôpital St. Elsewhere (1982), producer Glen A. Larson asked Daniels if he would read for the voice of a car in another series, which was K 2000 (1982). With memories of the infamous failure Une mère pas comme les autres (1965), he resisted, but Larson insisted it was a computer, not a car, talking, and coaxed Daniels into a small recording studio at Universal.

Nominated for a Tony as Supporting Actor in a Musical for his lead role of John Adams in the 1969 musical "1776." He could not be nominated for lead actor because he did not then have star billing (i.e., above the title). Adams is clearly the lead role in 1776 (1972), so Daniels declined the nomination.

Before he was a successful actor, he began his career in 1945, aged 18, he was drafted in Italy, where he served as an Army radio station disc jockey.

Worked conscientiously to lose the Brooklyn accent he grew up with, so that he could obtain a wider range of roles. His adopted accent is close to the Boston dialect he used as Dr. Mark Craig on Hôpital St. Elsewhere (1982) and Mr. George Feeny on Incorrigible Cory (1993).

In addition to portraying John Adams in 1776 (1972), he portrayed his son John Quincy Adams in La famille Adams (1976).

He got one of the lead roles as Dr. Mark Craig on Hôpital St. Elsewhere (1982), primarily because of his longtime friendship with Bruce Paltrow and his wife Blythe Danner.

Started dancing when he was 4.

He has played the same character (George Feeny) on three different series: Incorrigible Cory (1993), Maybe This Time (1995) and Le Monde de Riley (2014).

He and his wife, actress Bonnie Bartlett, won Emmys for their portrayals of a married couple, Dr. and Mrs. Mark Craig, on the cult TV series Hôpital St. Elsewhere (1982) in 1982.

His classmates at Northwestern included Paul Lynde, Georgann Johnson, and his future wife Bonnie Bartlett.

1949 graduate of Northwestern University.

His mother, Irene Daniels, was a telephone operator, and his father, David Daniels, was a bricklayer.

In 1936, at almost 9, Daniels began performing on children's radio, for the first time, with one of his sisters.

As of 2018, he has appeared in three films nominated for Best Picture Academy Award: Des clowns par milliers (1965), Le lauréat (1967) and Reds (1981).

Elected president of the Screen Actors Guild, upsetting incumbent Richard Masur, as well as candidate Angel Tompkins, who conjoined her two names to call herself "Angeltompkins" so she could be listed first on the ballot(!) The SAG president serves a two-year term. (November 1999)

Met Bruce Paltrow and Blythe Danner while working on 1776 (1972); in 1982, a decade later, he would work with them on Hôpital St. Elsewhere (1982).

Best friends of Ed Flanders and Norman Lloyd.

His sister is Carol "Termite" Daniels, who was a child radio star in the 1940s.

Met his future wife Bonnie Bartlett at Northwestern University.

His Hôpital St. Elsewhere (1982) co-star, Ed Begley Jr., would be the total opposite of him. Coming from film, Begley came in to work late, had trouble learning his lines, while Daniels learned a lot of lines, coming from the theater.

Best known by the public for his starring role as Dr. Mark Craig on Hôpital St. Elsewhere (1982) and for his role as George Feeny on Incorrigible Cory (1993) and Le Monde de Riley (2014).

Is a member of the Sigma Nu fraternity.

Lives not too far away from his ex-Hôpital St. Elsewhere (1982) co-star, Ed Begley Jr..

On Hôpital St. Elsewhere (1982), his character was originally from Boston, in real-life, he has the Boston accent, since he was 15.

On the Hôpital St. Elsewhere (1982) set, along with Ed Flanders and Norman Lloyd, Daniels had to pronounce medical terms using the medical dictionary. He also had to make a speech, before performing surgery.

Was born in the apartment that didn't have any tub nor shower.

He is the son of Irene (Bulger) and David Dryden Daniels.

Has three sons, William Jr. (died shortly after birth), Michael and Robert.

He endorsed Senator Bernie Sanders in the 2016 U.S. Presidential Election.