Anger - It's all in the EYES
Credits: "Gollum" in the live-action trilogy of "The Lord of the Rings," written by J.R.R. Tolkien and directed by Peter Jackson; produced by WingNut Films and The Saul Zaentz Company and distributed by New Line Cinema; 2001, 2002 + 2003.
Not only is anger dependent on the eye/brow interface to be recognized (there is no such thing as an angry mouth without angry eyes and brow), the wideness of the eyes controls the intensity of the anger.
Here the enraged Gollum is based on the excellent posing of the Glare, the eye configuration that creates the angriest possible face. The Glare is the combination of the upper eyelid being raised to its maximum height (note both the angle of the outer upper lid edge – more vertical than normal- and the fact that the lid line goes well above the iris) with the radically descended brow, clipping the inner edge of the iris. The grimace-like mouth appears sinister entirely based on the angry eyes; by itself it would just be a failed attempt at a smile (not wide enough, and too much display of the lower teeth). My book was a reference for the LotR team in NZ.