The actress, who was born in Bradford, West Yorkshire, had been fighting a long battle with cancer and died this morning in a London hospital.
Her agent Barry Langford confirmed the news and said she had a “zest for life”.
Meanwhile, Tom Baker, who played the fourth Doctor said: “She was a darling companion and wonderfully witty and kind, I’m so sorry to hear of her death.”
Colin Baker, who played the sixth Doctor, wrote on Twitter: “Shellshocked to hear Mary Tamm is gone. A funny, caring, talented, lovely and down to earth lady.”
Mary had been battling cancer for 18 months and her agent has revealed that she was saddened by recent deaths including Elisabeth Sladen. He said: “All of these people who she knew were going.”
The actress leaves behind husband Marcus Ringrose, daughter Lauren and seven-year-old grandson Max.
Our thoughts are with Mary’s family and friends at this upsetting time.