Garson's son, Nathen, shared a farewell message on Instagram on Tuesday night.
"You always were the toughest and funniest and smartest person I’ve known. I’m glad you shared your love with me. I’ll never forget it or lose it," he wrote.
Garson's colleagues took to social media to express their feelings regarding the loss; actress Cynthina Nixon, who plays the role of Miranda Hobbes in the Sex and the City series, said Garson was "endlessly funny on-screen and and in real life."
Willie Garson has appeared in over 75 films and more than 300 TV episodes.