countenance: A person’s face or facial expression.
grin: smile broadly, especially in an unrestrained manner and with the mouth open.
beam: a radiant or good-natured look or smile.
grimace: an ugly, twisted expression on a person’s face, typically expressing disgust, pain, or wry amusement.
frown: form an expression of disapproval, displeasure, or concentration, typically by turning down the corners of the mouth.
glower: have an angry or sullen look on one’s face
pout: push one’s lips or one’s bottom lip forward as an expression of petulant annoyance
browbeat: This is not a word for a facial expression, but I can’t help including it since it contains “brow”. It means intimidate (someone), typically into doing something, with stern or abusive words.
snarl: A snarl is a sound, often a growl or vicious utterance, often accompanied by a facial expression, where the upper lip is raised, and the nostrils widen, generally indicating hate, anger or pain
yawn: involuntarily open one’s mouth wide and inhale deeply due to tiredness or boredom.
scowl: an angry or bad-tempered expression.
smirk: smile in an irritatingly smug, conceited, or silly way.
simper: smile in an affectedly coy or ingratiating manner.
sneer: a contemptuous or mocking smile, remark, or tone.
leer: look or gaze in an unpleasant, malicious, or lascivious way.
guffaw: a loud, unrestrained burst of laughter.
smile (or grin) from ear to ear: have a big smile
tight-lipped: with the lips firmly closed, especially as a sign of suppressed emotion or determined reticence.
ruddy: (of a person’s face) having a healthy red color.
jaundice: Jaundice is a condition in which the skin, sclera (whites of the eyes) and mucous membranes turn yellow.