In an interview with Variety, "Guardians of the Galaxy" star Vin Diesel revealed that playing Groot helped him mourn his "Furious 7" co-star and friend Paul Walker, who passed away in 2013.

Vin Diesel recorded the role during a four month hiatus from "Furious 7," just after Walker's death. "Vin was in a very sensitive place," director James Gunn said. "It was not long after Paul passed away. I think the simplicity of Groot, the innocence of Groot and the creativity of Groot was a big relief for Vin."

"That was healing for me," Diesel said, "To play a character that could reincarnate, rejuvenate and represent life as trees do."

"It took a lot of time and meditation," he added. "[Groot] needed to have this guttural voice, without always being so menacing. I just played with it and played with it, and I was inspired by my 3-year-old son at the time, who I was playing the role for. I always imagined the character would have to connect to a child."

Marvel's "Guardians of the Galaxy" went on to earn $774 million at the box office.