The former Doctor Who star lost her 18-month battle with cancer in London this morning (July 26), her agent confirmed.
Tamm was perhaps best known for her role as Romana, the companion of Tom Baker's Doctor in the 1978-79 Key to Time series.
"She had a great zest for life. She was a fantastic actress - she played stage parts of such range, parts that would take your breath away. She could play any role, and do so wonderfully," her longtime agent Barry Langford told PA.
The stage and screen actress starred in a number of films including The Odessa File and The Likely Lads.
Following Tamm's role in Doctor Who, she featured in lead roles in shows including The Treachery Game, The Assassination Run and sitcom The Hello, Goodbye Man.
Tamm starred in Brookside from 1993 to 1996 as Penny Crosbie, and in EastEnders as Orlenda for a week-long storyline in 2009.
She also appeared in TV shows including Paradise Heights, The Bill, Doctors, Holby City and Wire in the Blood.
Mary Tamm spoke to Digital Spy in 2009 about her autobiography First Generation.
She is survived by her husband Marcus Ringrose, daughter Lauren and grandson Max.
Watch a clip of Mary Tamm and Tom Baker in Doctor Who below: