Thomas Jeffrey Hemsley, CBE (12 April 1927 – 11 April 2013) was an English baritone.
Hemsley was born in Coalville, Leicestershire. He made his debut in 1951 as Aeneas in Purcell's Dido and Aeneas at the Mermaid Theatre, London, alongside Kirsten Flagstad as Dido. The pair recorded the opera for EMI the same year. He debuted at Glyndebourne in 1953. He was principal baritone at the Aachen Opera from 1953 to 1956, the Deutsche Oper am Rhein from 1957 to 1963, and the Zürich Opera from 1963 to 1967.
In 1960 he created the role of Demetrius in Britten's A Midsummer Night's Dream with the English Opera Group at Aldeburgh.
In 1965 he was the baritone soloist in only the second UK performance (and only the fourth performance in the work's history) of Delius's Requiem, in Liverpool, under Charles Groves.
He was a notable interpreter of Beckmesser in Wagner's Die Meistersinger von Nürnberg, performing the role at Bayreuth from 1968 to 1970 and recording it under the baton of Rafael Kubelík.
He made his Covent Garden debut in 1970 creating Mangus in Tippett's The Knot Garden, and in 1974 at the Scottish Opera he created Caesar in Iain Hamilton's opera The Catiline Conspiracy.
In the latter part of his career he taught at the Guildhall School of Music and Drama, London and also Dartington International Summer School.
Hemsley died on 11 April 2013, one day before his 86th birthday.