The son of Sir George Martin and his first wife, Sheena (née Chisholm), Gregory Martin attended Britain's St Albans School and trained as an actor at the Royal Academy of Dramatic Art in London, studying alongside Juliet Stevenson and Alan Rickman.
Martin's acting roles in the British theater include the world premiere of Bent (1979), at The Royal Court in London with Sir Ian McKellen, a season at the Bristol Old Vic, and seasons at London's Old Vic and Young Vic theaters. His American theater credits include the title roles in Hamlet and Peer Gynt at the Guthrie Theater in Minneapolis, as well as the American premier of Harold Pinter's Other Places, at The Manhattan Theater Club in New York City.
Martin appeared opposite Faye Dunaway, Liam Neeson, and Richard Burton in the 1984 CBS mini-series Ellis Island. He made appearances in a number of television series of the 1980s-1990s, including Murder, She Wrote, Sliders, Babylon 5, and Mad About You.
Martin appeared in the movie Memoirs of an Invisible Man (1992), alongside Chevy Chase and Daryl Hannah, and A Walk in the Clouds, opposite Keanu Reeves and Anthony Quinn.
In recent years, Martin has focused on script writing. His personal website says he sold a script for a movie called Tsunami, optioned as an ABC miniseries, and a script for a movie called Ice as a sci-fi action thriller set in Antarctica. In 1998 Martin returned for a brief period to England and started a film and television production company, according to his website.
After receiving poor treatment from the British tabloid press, he left England again, determined not to return. In 2000, he published a satirical memoir, Dirty Rotten Scoundrel, which was based in part on his treatment in the tabloids. In describing this work, Martin says:
"I wrote this book as a satire of an ugly image foisted on me by the British tabloids during the summer of 1999, and was never intended to be taken seriously. I take it as an oddly flattering compliment people assumed the character was really me."
A Guardian review of the book, which apparently did take it straight rather than as satire, says his reputation in the UK was badly damaged with a failed engagement to a socialite in 1999 that became tabloid fodder. The Guardian says of his book:
"A diary of his years at Rada and in the film and TV business in the US (among other things, he starred in Ellis Island, and co-starred in Ellen) as well as the events of last year, it is full of 'birds' and 'horny little slappers', of 'sexy young blueblood vixens', and 'gorgeous, sweet, hot-as-a-chilli-pepper-ridden-chicken-vindaloo beauties.'"
After returning to the US, Martin resumed script writing and also got involved in advertising and brand marketing, according to his website.
After his move to Hollywood during the 1980s, Martin married, and he and his wife had a son, Connor. The marriage ended in divorce. He is currently married to Cherie Martin.A Walk in the Clouds - Armistead Knox
Ellen - Roger
SeaQuest DSV - Marcus Rawlings
Babylon 5 episode "Eyes" (1994) - Colonel Ari Ben Zayn
Mad About You - Andrew
Empty Nest - Ian
Memoirs of an Invisible Man - Richard
Murder, She Wrote - Danny Briggs
Sliders - Gareth
Ellis Island - Marco Santorelli