Kristin Hayter (born June 17, 1986) is an American singer and pianist. She started releasing music in 2017 and performed under the Latin name Lingua Ignota ('unknown language'). In 2023, citing the unhealthiness of reliving her trauma through her performances, Hayter retired the Lingua Ignota project. She embodied a new persona under the moniker Reverend Kristin Michael Hayter.

Her professional music career began in 2017 with the self-released albums Let the Evil of His Own Lips Cover Him and All Bitches Die, which spread through word-of-mouth. Hayter's music caught the attention of Profound Lore Records, who re-issued All Bitches Die and released her third studio album, Caligula, in 2019, which was met with universal critical acclaim. Her fourth album, Sinner Get Ready, was released in 2021 on Sargent House and received more widespread critical acclaim. Her work as Lingua Ignota drew from her experiences as a survivor of domestic violence for musical and lyrical inspiration, and she describes her music as "survivor anthems". Her debut album as Reverend Kristin Michael Hayter, Saved!, came out in 2023.