William Friedkin's finest film in my opinion. To Live and Die in L.A. has been so relentlessly plagiarised and approximated over the past three decades that it deserves a shot at a place in the Canon just because most people haven't seen it. Also: it's heart-stoppingly brilliant.
There's a single plot twist (instantly discarded in Friedkin's film) that has been copied so many times that I'm genuinely annoyed whenever isn't given credit.
It also launched Willem Dafoe, as well as the unappreciated John Pankow and William Peterson.
One off the few 80s films that I regard as an unarguable masterwork.