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 in Heaven 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.)

Upon learning that the Eleventh Doctor had shaved his head, Clara Oswald questioned if he had shaved his eyebrows as well only for him to self-consciously defend them as "just delicate". (TV: The Time of the Doctor) The Twelfth Doctor by contrast 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)

Romana II asked the Fourth Doctor why the Mona Lisa didn't have any eyebrows. He started to chide her for asking this, but then realised for the first time that the Mona Lisa didn't. (TV: City of Death)

The Fourteenth Doctor told a group of his former companions and their family members a story about a species which communicated only with their eyebrows. (TV: The Giggle ^[+]Russell T Davies, Doctor Who 2023 specials (BBC One and Disney+, 2023).)

Aiming to treat his leukaemia while he still had eyebrows, Jamie Burton decided to undergo a second round of chemotherapy. (TV: Dead Man Walking ^[+]Matt Jones, Torchwood series 2 (BBC Three, 2008).)

There was a noticeable slit on Ruby Sunday's right eyebrow. (TV: The Church on Ruby Road ^[+]Russell T Davies, Doctor Who Christmas Special 2023 (BBC One and Disney+, 2023)., et al.)