Saint Chroma (commonly known as St. Chroma) is the main character of Tyler, The Creator's 8th studio album, Chromakopia. He is a paranoid, presumed Drill Sergeant that owns a trucking company titled "Chromakopia", and is most known for the iconic mask he wears in all promotional material regarding Chromakopia.
Chromakopia's album cover is a portrait of Saint Chroma. He has also appeared in every music video for this album, sporting a green military-style uniform and a mask that resembles (but covers) his face. Due to Tyler's asthma, the lower half of the mask is usually absent during live performances. In the music video for Thought I Was Dead, he lacks a mask and during live performances of Take Your Mask Off, as the name suggests, he takes off the mask during the chorus.
Based on the lyrics found throughout the album, Saint Chroma is very insecure and is scared about opening up, wearing a mask to make it easier. Multiple tracks on the album are stories about Tyler's personal life, an example being Judge Judy.