He is perhaps best remembered for his role as detective John Bosley, the naive and sometimes comical but clever private investigator on Charlie's Angels, for which reason he is occasionally mixed up with TV actor Tom Bosley. He is also remembered by younger generations as being the voice of Grandpa Lou Pickles on the Nickelodeon animated television series Rugrats until his death. Doyle died of a heart attack at the age of 67 in Los Angeles, California on February 26, 1997.

John Bosley "Boz" John Bosley (often nicknamed "Boz") is a middle aged man of average looks, especially when contrasted with the glamorous "Angels". However, he is warm, funny, and intelligent, and often helps the Angels either with background information, or often joining them in the field. Seemingly asexual (and thus unthreatening), he helped direct the Angels meet Charlie's desired ends in the series where most men were villains and women were often victims (outside the Angels themselves). Several times he played either a pratfall-type character or a Sugar Daddy as part of one of the Angels' covers. Bosley always initiates the phone conferences between Charlie and the Angels as they learn of each case. He also acts as a father figure to the ladies.

Bosley is apparently the only Townsend Agency employee to have ever met Charlie, and he remains steadfast in never revealing Charlie's identity, or even a clue to his looks. This was a running joke in the series. Most of the Angels found themselves romantically involved at one time or another with someone they encountered on the job, and Bosley is no exception. He became linked with several females encountered in cases, although always those of middle age. One particularly close relationship occurred when the Angels visited Aspen, Colorado in Season 3. However, these liaisons never seemed to last beyond the episode, and otherwise, we learn little about Bosley's private life. Ironically, although Bosley is proficient with firearms, his actions occasionally hampered the Angels' work. In one episode, Bosley, acting as an Auctioneer, gets caught up in the excitement and mistakenly sells valuable merchandise not to an Angel as per the plan, but to an actual bidder. This ruined the Angels later plan to catch a cat burglar.

Doyle entered the University of Nebraska in 1945 and he was expected to become a lawyer, as had four generations of Doyles. But the young Doyle preferred to spend him time in the theater department. A fellow classmate at the University of Nebraska was Johnny Carson. Doyle appeared frequently on his college buddy's late night talk show during the 1960s. Doyle ranked sixth in the state on his law school entrance exams. But the theater still called him and he chose acting over a career in law. He moved to New York after college and took three months of formal drama training before going into the Navy for four years. After the service he came back to New York in 1954 and starting appearing in Broadway. He got his first theatrical break in 1956 when he replaced Walter Matthau in the Broadway production of  "Will Success Spoil Rock Hunter?" with Jayne Mansfield and Tom Poston. And that was just the beginning. From there he did about 12 Broadway shows.

He subsequently spent several seasons as an actor/director in a Midwestern traveling stock company, then returned to New York, where he appeared in S.J. Perelman's "The Beauty Part" and seven other Broadway plays. He also appeared in  "Something For a Soldier"  with Sal Mineo. His first wife, Rachel, died after injuries in a freak fall from a stairway in 1968. While doing a revival of "South Pacific" a year later at the Lincoln Center in New York, he met former singer-dancer Anne Nathan and they were married. He stayed in New York from 1954 to 1972 doing shows on and off Broadway and appeared in various films and commercials and then moved with his family to California.

After a decade's worth of film and TV supporting appearances and commercials, Doyle was cast in the recurring role of Walt Fitzgerald in the 1972 television sitcom "Bridget Loves Bernie." That same year, he made semi-weekly visits to "The New Dick Van Dyke Show" in the role of Ted Atwater.

He has also been seen as Frank Macklin on the short-lived 1987 series "Sweet Surrender" and heard as the voice of Grandpa Pickles on the Nickleodeon cable network's animated series Rugrats (1991) on the first sixty-five episodes and recorded several later episodes as well. Doyle had a sister who was mostly a stage actress, Mary Doyle, who died from lung cancer in 1995. Although sandy-voiced character actor David Doyle sometimes gave the onscreen impression of being an unprepossessing, slow-on-the-uptake "little man," in truth Doyle stood six feet tall, weighed 200 pounds, and had an I.Q. of 148.