Eyebrow

The eyebrow was an area of hair located above the eye. Raising an eyebrow was a common method of showing interest, (PROSE: Christmas on a Rational Planet, The Eyeless, et al) so much so that there was a raised eyebrow emoji. (TV: Smile)

Due to an incident in the War involving the Fendahl Predator, (PROSE: The Taking of Planet 5) the Delphon communicated using only their eyebrows. (TV: Spearhead from Space, AUDIO: The Havoc of Empires, et al)

The Twelfth Doctor was noted to have very large "attack" eyebrows, (TV: Deep Breath) with Missy even giving him the nickname "the Eyebrows". (TV: The Witch's Familiar)