Derek Oldham (29 March 1887 – 20 March 1968) was an English singer and actor, best known for his performances in the tenor roles of the Savoy Operas with the D'Oyly Carte Opera Company.

After performing in concerts as a boy soprano and working as a bank clerk, Oldham began a professional performing career in 1914. With the outbreak of World War I, he joined the Scots Guards, serving with valour. After the war, he joined the D'Oyly Carte Opera Company, singing the tenor leads in the Gilbert and Sullivan operas for three years. He then starred in musicals and operettas in the West End in the 1920s, including Madame Pompadour, The Merry Widow, Rose-Marie and The Vagabond King. He returned to the D'Oyly Carte for brief periods from 1929 to 1937.

Oldham continued singing, recording and acting through the 1940s, also appearing in several films. He concentrated on legitimate theatre in the 1950s, acting until the age of 70. He maintained a lifelong interest in Gilbert and Sullivan, serving as an officer of the Gilbert and Sullivan Society. He finally retired to Hampshire during the last ten years of his life.