The actress, who played Narcissa Malfoy in the film series, lost her battle with cancer at her home in London and Tom has taken to Instagram to thank her for influencing his own career.
The actor, who played her son Draco Malfoy in the "Harry Potter" franchise, wrote, "So sad to say farewell so suddenly - I never took the chance to tell her, but she helped shape me as a person so much - on & off screen - She was always relentlessly herself - razor sharp wit - silver tongued - kind & warm hearted - she suffered no fools yet had time for everyone - thank you for lighting the way forward & holding my hand when I needed it."
His movie father, Isaacs, who portrayed Narcissa's evil husband Lucius, added, "Decades ago Helen and I auditioned together for a film. I came home and said to (my wife) Emma (Hewitt), 'I think I've just met the greatest actress I've ever seen.' "
"After years of watching her mesmerize audiences I don't think that any more... I know it."
He added his late co-star was "scabrously funny, shockingly naughty and with an empathetic heart the size of a planet."
"As continually starstruck as I was on the Harry Potter films, being screen-married to and giggling with the great Helen McCrory will always be a highlight," he wrote. "Her proudest achievement, though, was building and loving the family that was her bedrock. They've lost so much and I send all my love to Damian and the kids."
He has since added a new statement in an op-ed piece for The Sunday Times, calling her "an even more brilliant person than she was an actress."
"I've never known anyone so consciously spread happiness," Lewis wrote, explaining nurses who were caring for his late wife towards the end of her life looked forward to seeing her "because she made their day better."
"I've never known anyone able to enjoy life as much," Lewis added. "Her ability to be in the present and enjoy the moment was inspirational. Nor was she interested in navel-gazing. No real self-interest in self-reflection; she believed in looking out, not in. Which is why she was able to turn her light so brightly on others..."
"Already I miss her. She has shone more brightly in the last months than you would imagine even the brightest star could shine. In life, too, we had to rise to meet her. But her greatest and most exquisite act of bravery and generosity has been to 'normalise' her death."
"She's shown no fear, no bitterness, no self-pity, only armed us with the courage to go on and insisted that no one be sad, because she is happy. I'm staggered by her. She's been a meteor in our life."