Rupert Grint (Ron Weasley)
What he looked like then: This guy Todd I went to elementary school with
What he looks like now: A 1970s drummer with some inner demons
I feel like Rupert Grint has played this exact role in multiple movies. The closest thing I can find is CBGB, in which he played punk rock guitarist Cheetah Chrome, but he gives off similar vibes in Wild Target and Cherrybomb.