During his eight-year run on the popular sitcom, Wilder worked closely with Danny Masterson – who was recently sentenced to 30 years in prison for rape – and they also reunited for an episode of Netflix's The Ranch, starring Ashton Kutcher, in 2016.
Danny, a member of the Church of Scientology, was accused of raping three women at his Hollywood Hills home between 2001 and 2003.
The star, who was famed for portraying Steven Hyde in That '70s Show, has always maintained his innocence.
But what has Wilmer said about the sentencing of his co-star? And what has he revealed about his friendship with Danny in the past? Here's what we know.
Has Wilmer Valderrama commented on Danny Masterson's sentencing?
Wilmer is yet to publicly comment on the sentencing of Danny Masterson. Following a lengthy court case, the latter has received 30 years in prison after being convicted of rape.
After Danny's sentencing, it was revealed that his That '70s Show co-stars Ashton Kutcher, Mila Kunis, Debra Jo Rupp and Kurtwood Smith had all submitted character reference letters on his behalf.
Topher Grace, Laura Prepon and Wilmer Valderrama have refrained from doing so.
In her letter to the court, Debra Jo Rupp spoke of Danny's friendship with the cast and recalled the time he'd attended Wilmer's high school graduation.
"Wilmer Valderrama asked the cast of 70's Show to go to his high school graduation," she penned. "Danny and I were the only ones to go. I remember looking at him and dying. It was outside, in the valley, really hot, and he was a 'V' alphabetically. We laughed so hard during that. It's a really nice memory. Danny just always showed up to support."
What had Wilmer Valderrama said about Danny Masterson prior to his trial?
Before allegations were made against Danny Masterson, Wilmer had maintained a close friendship with the actor, and he was even spotted celebrating his birthday with Danny and their That '70s Show cast members at a dinner in 2015.
A year later, when Wilmer reunited with Danny and Ashton for an episode of The Ranch, the NCIS star said that they'd had a lot of fun on set.
"The three of us are hooligans laughing our [expletive] off and being clowns and not really taking the takes serious and then having them yelling at us like we were 20 again, and that to me was so worth being there all day," he told E!.
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