"With a gentle hand and heart Jean-Marc was a true receiver — he didn't romanticise life so much as he saw life romantic — from the struggle to the pain to the wink and the whisper, love stories were everywhere in his eye," tweeted McConaughey, one of several stars paying tribute to Vallée on Monday.
Vallée often shot with natural light and hand-held cameras, giving actors freedom to improvise from the script and move around within a scene's location. The crew roamed up and down the Pacific Coast Trail to shoot Witherspoon in 2014′s Wild.
"They can move anywhere they want," the Canadian filmmaker said of his actors in a 2014 interview with The Associated Press. "It's giving the importance to storytelling, emotion, characters. I try not to interfere too much. I don't need to cut performances. Often, the cinematographer and I were like, 'This location sucks. It's not very nice. But, hey, that's life'."
He re-teamed with Witherspoon to direct the first season of Big Little Lies in 2017, and directed Adams in 2018′s Sharp Objects, also for HBO. Vallée won DGA awards for both.
"I will always remember you as the sun goes down," Witherspoon wrote on Instagram along with a series of photos of the director. "Chasing the light. On a mountain in Oregon. On a beach in Monterey. Making sure we all caught a little magic in this lifetime. I love you, Jean Marc. Until we meet again."
Her Big Little Lies co-star Laura Dern on Instagram called Vallée a "beloved friend" who was "one of our great and purest artists and dreamers".
Leto said on Twitter that he was "a filmmaking force and a true artist who changed my life".
And Canadian Prime Minister Justin Trudeau tweeted that "Jean-Marc Vallée's passion for filmmaking and storytelling was unmatched — so too was his talent. Through his work and with his art, he left a mark in Quebec, across Canada, and around the world".