Mozart's Requiem in D minor (K. 626, 1791) is his final and unfinished composition, left incomplete at his death and later completed by his student Franz Xaver Süssmayr. This first part encompasses the Introit, Kyrie, Dies Irae, Tuba Mirum, Confutatis, and Lacrimosa, movements that have become some of the most iconic in the choral repertoire.
Source
Public Domain