Anthony Defries (born 3 September 1943) is a British former music manager and impresario. He managed David Bowie's career during his elevation to global stardom, but later fell out with him in a contract dispute. He established a rights management organisation called MainMan and helped launch the careers of Iggy Pop, Mick Ronson, Mott the Hoople, Dana Gillespie, Lou Reed, Luther Vandross and John Cougar Mellencamp. Defries and MainMan have received multiple awards for their achievements in the music industry.

One of four children born to Edward and Lily Defries, the family had a second-hand and antique business close to Shepherd's Bush Market. In 1944, children were being evacuated from London to escape the V-1 flying bombs. Defries was too young to be evacuated as his mother had two young children and was expecting another, so he was placed into foster care and returned to the family after the war. He suffered from severe asthma and attended a school for children with special needs.

Defries started his career at the age of 16 in a number of junior positions at various firms of solicitors. While he was a legal executive at the lawfirm of Martin Boston & Co. in Wigmore Street, London he advised Mickie Most in a dispute involving The Animals in 1964. For some years after that he worked with Most, advising him and later working with Allen Klein on his behalf and helping Mickie set up his own independent label Rak Records, and music publishing Rak Publishing. Defries learnt about bargaining techniques, the intricacies of master recording ownership and how to squeeze the best from every deal from Klein. Because of his dealings with Most and his problem-solving abilities, he was approached by his future business partner, Laurence Myers, whose accounting firm were handling Most's accounts at the time. Myers said "Tony was a visionary. I remember him telling me many, many, many years ago that one day everyone at home will have a laptop computer".

Defries later worked with photographers to resolve their copyright and other issues, starting with Don Silverstein, an American photographer living and working in London, who had taken photographs of Jimi Hendrix. These images were being used without his permission and Defries helped him retain the rights to his images and the related revenue. Through Silverstein, Defries was approached by other photographers such as Brian Duffy, David Bailey, Terence Donovan and Antony Armstrong-Jones. To best assist them, and future photographers, he helped found the Association of Fashion and Advertising Photographers (AFAP), in 1968, which later became the Association of Photographers (AOP). Defries would later commission Brian Duffy to photograph and design the cover of Bowie's Aladdin Sane, and Terry O'Neill to shoot the Diamond Dogs album cover. In addition MainMan commissioned rock artist Guy Peellaert to provide futuristic paintings which were ultimately used for that album.

Defries and Myers worked with songwriters, composers, performers and producers, including Mike Leander, Geoff Stephens, Peter Eden, Barry Mason, Roger Cook, Mike D'abo, Donovan, Roger Greenaway, Lionel Bart, Neville Nixon, Ossie Byrne and Tony Macaulay. Defries was responsible for proposing and overseeing legal proceedings for Tony Macaulay in what became a landmark case against his publishers, Schroeder Music, to recover his copyrights. The case of Schroeder Music Publishing vs Macaulay was resolved in Macaulay's favour in the House of Lords, setting a precedent used by many other songwriters to gain better terms.

In 1969, Defries and Myers formed the GEM Music Group, an independent music label, music publishing, rights management and personal management company. GEM's first release, on Bell Records, was "Love Grows (Where my Rosemary Goes)" performed by Edison Lighthouse, and written and produced by Tony Macaulay. It reached number one on the UK Singles Chart in 1970.

In 1970, Olav Wyper, the head of Philips UK, recommended Defries to Bowie who was dissatisfied with his manager Ken Pitt and needed help. Defries realised Bowie's potential and Myers has said "Tony had the vision. His great ability was, far more than I did, he knew what a star David was going to be". Defries had a reputation for renegotiating contracts and proceeded to extract Bowie from all his existing contracts: management, recording (Mercury) and publishing (Essex Music). GEM signed an exclusive contract with Bowie in 1970 and when the Mercury contract was terminated in 1971, Defries was free to sign a record deal with RCA. Defries would go on to sign Iggy Pop, Dana Gillespie and Mick Ronson with GEM.

In 1971, Defries had decided that breaking Bowie in the US would require a permanent corporate presence and suggested to Myers that they open offices in New York. By that time, GEM had established a significant position in the UK industry and Myers was uncomfortable about risking that base in a new US venture. As a result, Defries and Myers discussed a division of the various talent GEM represented and reached a settlement which would allow Defries to keep certain artists while the rest remained with GEM. They signed an agreement where Defries would take David Bowie, Iggy Pop, Mott the Hoople, Dana Gillespie and Mick Ronson in return for a financial settlement.