Daniel Radcliffe. Radcliffe admits candidly that he ended up becoming a ‘party focused guy’ that used alcohol as a means to coping. His on screen performance in several of the later Harry Potter films is notable due to the fact that Radcliffe admitted to being ‘mostly intoxicated’ throughout the filming. Daniel managed to get himself into rehab, clean up, and get back on the straight and narrow again.
Harry Potter stress led to Daniel Radcliffe's alcohol problem
Daniel Radcliffe used alcohol to cope with end of Harry Potter
Daniel Radcliffe Reveals Secret Alcohol Addiction - Us Weekly