Regret

Regret may refer to the following:
 * Prophet of Regret - The San'Shyuum hierarch during the Human-Covenant War.
 * Regret (achievement) - An achievement in Halo 2 Vista and Halo: The Master Chief Collection.
 * Regret (level) - The ninth campaign level in Halo 2 which requires the player to kill the Prophet of Regret.
 * Regret (Halo 5: Guardians level) - The Halo 5: Guardians multiplayer map based on a Covenant ship that crashed on a Halo ring.
 * Regret (music) - A soundtrack from the Halo: Spartan Assault Original Soundtrack.