That sucks. Apparently a smack overdose. One of the better actors in the past decade IMO.
https://www.nytimes.com/2014/02/03/movies/philip-seymour-hoffman-actor-dies-at-46.html?_r=0
https://www.nytimes.com/2014/02/03/movies/philip-seymour-hoffman-actor-dies-at-46.html?_r=0