Frederic Sullivan (25 December 1837 – 18 January 1877) was an English actor and singer. He originated the role of the Learned Judge in Gilbert and Sullivan's 1875 comic opera Trial by Jury, providing the model for the comic roles in the later Savoy operas.
Born into a musical family, he initially trained as an architectural draftsman but, in 1869, abandoned the profession for a career on stage. In 1871, he first performed the role of Mr. Cox in a revival of his brother Arthur's first comic opera, Cox and Box, and later that year created the role of Apollo in the first Gilbert and Sullivan opera, Thespis. He then remained with the Gaiety Theatre company, playing in Jacques Offenbach pieces, among others. In 1874 he played in comic operas on tour and in other London theatres.
In 1875, he created the role of the Learned Judge in Trial by Jury, also playing in the accompanying Offenbach piece, La Périchole, and earning enthusiastic reviews. He then toured in Trial, and French operettas, returning to London for the revival of Trial. By early 1876, Sullivan's health was deteriorating, and he was forced to stop performing in October 1876. He died in January 1877, leaving a pregnant widow and seven young children. His brother Arthur's enduring song, "The Lost Chord", was composed at Fred's bedside. After Fred's death, Arthur became guardian to the children and helped support Fred's family for the rest of his life even after they moved to California against his wishes. He left the bulk of his estate to Fred's children.