Robert Louis Colbert (born July 26, 1931) is an American retired actor best known for his leading role as Dr. Doug Phillips on the ABC television series The Time Tunnel and his two appearances as Brent Maverick, a third Maverick brother in the ABC/Warner Brothers western Maverick.

Robert Louis Colbert was born in Long Beach, California, on July 26, 1931, the son of Helena (née Gorman) and Clarence Colbert. He began acting when he was a soldier based on the Japanese island of Okinawa. He was a clerk typist with a Military Police unit and also worked as a disc jockey for radio station KSBK in the evenings. A woman in Air Force Special Services heard his voice and recruited him to act in a performance of The Caine Mutiny Court-Martial. He gained acting experience with the Portland (Oregon) Repertory Theater.

Colbert appeared in a number of minor films, including Have Rocket, Will Travel with the Three Stooges. He was signed to a contract with Warner Bros. and subsequently cast in the feature film A Fever in the Blood (1961) with Jack Kelly and Efrem Zimbalist Jr., along with many guest appearances on Warner Brothers Television series.

In 1960, he appeared in three episodes of the ABC/WB western, Colt .45 with Wayde Preston, including the episode "Showdown at Goldtown". Colbert plays Johnny Moore, a young ex-convict. Colbert also appeared as Bill Mannix in another 1960 Colt .45 episode, "Strange Encounter."

On October 28, 1960, Colbert was cast as Army Corporal Howie Burch in the episode "Two Trails to Santa Fe" of the ABC/WB western series Cheyenne starring Clint Walker.

Colbert's first appearance in Maverick was in the fourth season, in "Hadley's Hunters," playing a character called "Cherokee" Dan Evans, an episode featuring many cameos by the lead actors in other Warner Bros. Western series playing their usual roles: Will Hutchins as Sugarfoot, Ty Hardin as Bronco, Clint Walker as Cheyenne, and John Russell and Peter Brown from Lawman. Colbert wore a black hat on the back of his head during the episode, the way James Garner's character had in earlier seasons (Garner and Colbert resembled each other extremely closely). Later that same season, in 1961, Colbert was forced by Warner Bros. to wear the whole costume, dressed exactly as look-alike Garner had in Garner's earlier role of Bret Maverick to play a new series regular called Brent Maverick. Thinking of the inevitable comparisons to Garner that were bound to ensue, Colbert said to his bosses, "Put me in a dress and call me Brenda, but don't do this to me!" Garner had been a huge success in the role and was in the process of moving into a much-anticipated theatrical movie career in the wake of winning a contentious lawsuit with Warner Bros. Colbert played his part in two episodes and was not called back for the following season since the studio, facing a steep ratings decline after the departures of writer/producer Roy Huggins and star Garner, agreed to alternate new episodes featuring only Bret and Brent's brother Bart Maverick (Jack Kelly) with reruns from earlier seasons starring Garner during the series' fifth and final season. Colbert, whose only two episodes as Brent Maverick were "The Forbidden City" and "Benefit of Doubt," had never received enough screen time to see if he could have eventually succeeded in bolstering the ratings.

Before Roger Moore, who played Bart's cousin Beau Maverick, left Maverick during the same season in which Colbert appeared, the studio shot numerous publicity photographs of Colbert, Kelly and Moore cavorting in costume together that are readily accessible on Google Images; the rights to many of the pictures are currently owned by Getty Images. By the time Colbert's two episodes were telecast, however, Moore had already quit the show and Moore and Colbert never appeared together in the series itself. James Garner reminisced in his Archive of American Television interview that the studio lit Colbert darkly as well as dressing him like Garner in an attempt to mislead the public that Garner had returned but that when Colbert spoke, the audience realized that it wasn't Garner.^{[citation needed]} A viewing of the episodes themselves, however, reveals that Garner was mistaken about this and that Colbert was lit normally during his shows although he was certainly dressed precisely as Garner had been earlier in the series.^{[citation needed]}

In 1962, Colbert appeared as Miles Kroeger on the TV western The Virginian on the episode titled "Impasse." In 1962, Colbert played Lonzo Green in the episode "Footlights" of the ABC/WB crime drama, The Roaring 20s. Moreover, he guest starred on most of the ABC/WB series, including 77 Sunset Strip and Hawaiian Eye (seven times each), Bronco (six times), Bourbon Street Beat (three times), Sugarfoot, The Alaskans with Roger Moore, Twelve O’Clock High, and Surfside 6 (twice each), and Cheyenne and Lawman, once each.