George Mortimer Roberts (known as "Mr. Bass Trombone") (March 22, 1928 - September 28, 2014) was an American trombonist.

Born and raised in Des Moines, Iowa, Roberts began his career after service in the US Navy with the Ray Robbins Band, and then quit to join Gene Krupa in 1947, where he was in the same section with Urbie Green. It was Urbie's lyric tenor trombone playing that inspired George to be an "Urbie" one octave lower.

When the Krupa band broke up in 1949, George played freelance in Reno for a year before being hired into the Stan Kenton Orchestra from 1950 until 1953, to replace Bart Varsalona, who had left the band during its 1949-50 hiatus. Roberts opted to stay in Los Angeles rather than go with Kenton on his 1953 European tour, and began working as a freelance substitute. He was introduced to Nelson Riddle by Lee Gillette, one of the executives at Capitol Records who had produced Kenton recordings. George soon launched a successful studio recording career with Riddle, Don Costa, Billy May, Axel Stordahl, Gordon Jenkins, Henry Mancini, among others, in sessions with Frank Sinatra, Tony Bennett, Ella Fitzgerald, Judy Garland, Sarah Vaughan, Nat King Cole and many others.

As a Hollywood studio musician, Roberts recorded numerous film scores with all the major studios (Jaws, King Kong, Close Encounters of the Third Kind, etc.) and served on the staff orchestras of the major radio and television networks (The Carol Burnett Show, Dinah Shore Show, Academy Awards, etc.). He eventually appeared on over 6000 recordings before retiring.

Roberts died on September 28, 2014, at the age of 86 in Fallbrook, CA, from pneumonia. He also had multiple sclerosis.