He is best known for having served as musical director/composer for Warner Brothers' /Leon Schlesinger's Looney Tunes and Merrie Melodies cartoon shorts from 1933 to 1936.
Beginning in 1919 he was credited as a songwriter for many songs as well as writing scores for musical stage shows.
Spencer served as composer and director of music for Leon Schlesinger Productions from 1933 to 1936, along with fellow composer Bernard Brown, creating film scores for animated short films in the Looney Tunes and Merrie Melodies series produced by Leon Schlesinger.
However, an article published on August 3 of the same year reported that Spencer had resigned and that Carl Stalling was succeeding him as the studio's music director.
[1] According to the article, Schlesinger had already signed a new contract with Spencer, only to hire his replacement a few months later, following Brown's departure to head the sound department for Universal Studios.