Anger was an emotion. In its deepest form, anger could turn to rage.
In response to negative emotions such as fear, grief and anger, humans once took medication in the future, to remove and override them. (AUDIO: Harvest of the Sycorax)
The Tenth Doctor once stated that he could get "so much more [angry]" than he was currently when he discovered that a Floof had killed Kathy. (PROSE: Corner of the Eye)
An emotional amplifier uncovered by Torchwood Three amplified anger into rage - so much so that Gwen Cooper feared she could have killed Rhys Williams. (PROSE: Slow Decay)
Tanya Adeola fed the Lankin anger, not grief, poisoning it, which left it in a weakened state. (TV: Nightvisiting)
When Bill Potts was upgraded into a CyberMondan, the Twelfth Doctor warned that she could no longer lose control of her anger, lest she trigger her cyber-weapon. She later "got angry" at a rusted over service hatch, cutting through it so that Nardole could evacuate the Mondasians. (TV: The Doctor Falls)
Behind the scenes[]

Unikitty in a state of anger. (NOTVALID: Endless Awesome)
References in invalid sources[]
When angry, Unikitty's colour scheme changed to mostly red and yellow. (NOTVALID: Endless Awesome)