Theaflavin (TF) and its derivatives, known collectively as theaflavins, are antioxidant polyphenols that are formed from the condensation of flavan-3-ols in tea leaves during the enzymatic oxidation (sometimes erroneously referred to as fermentation) of black tea.

Theaflavin-3-gallate, theaflavin-3'-gallate, and theaflavin-3-3'-digallate are the main theaflavins.

[1] Theaflavins are types of thearubigins, and are therefore reddish in color.