A children's football club chairman said he was "moved to tears" by a £1,600 donation by Ryan Reynolds.
FC United of Wrexham set up an online appeal to raise £480 for new kits for their under-12 futsal team.
However, Hollywood star Reynolds, who co-owns Wrexham AFC, donated more than triple the amount himself.
Kayleigh Barton, who set up the appeal and whose son Keegan plays for the team - said she was left shaking in disbelief after seeing the donation.
"It was just to help with the costs of the kits for the boys, so I just did it and I didn't expect Ryan Reynolds to donate the money," the 33-year-old told BBC Radio Wales Breakfast.
"I had an email saying that a Ryan had donated £600, and I just thought 'who's Ryan?'
"I logged in and it said Ryan Reynolds and I just said 'oh my god', I started shaking I just couldn't believe it."
She said her son, 11-year-old Keegan, suddenly lost his dad Adam - also a football player - last September, and that playing football helped him cope with the loss.
She said Keegan was "overwhelmed" by the donation, and would not even believe her when she first told him.
"He said 'I wish my dad was here now so I could tell him' and that just broke me," Kayleigh added.
"I said to him 'you're doing your dad proud, you keep going, you're going to follow in his footsteps and you're going to be a legend like he was'."
Club chairman Andrew Ruscoe, who initially messaged the movie star hoping for a retweet, said the donation was a "lifeline".
"I could see [the appeal] wasn't getting the attention needed, so I thought 'why not'. I dropped a message to Ryan to see if he could just retweet it initially, I didn't expect him to donate because I always feel that's a bit cheeky," he said.
"The next minute, just in the midst of Kayleigh ringing me, and I got a notification on my phone that just said 'enjoy the uniforms'.
"I'm in disbelief at this point, and near enough moved to tears, and I just said 'it's true Kayleigh, it's absolutely true'."
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