In music, the cross motif is a motif.
A motif (Crux fidelis) was used by Franz Liszt to represent the Christian cross ('tonisches Symbol des Kreuzes' or tonic symbol of the cross) and taken from Gregorian melodies.
Pyotr Ilyich Tchaikovsky associated a motif with the crucifixion, himself, and Tristan, a variation of which first appears in mm.1-2 of his Pathétique Symphony. Tchaikovsky identified with and associated the cross-motif with "star-cross'd lovers" in general, such as in Romeo and Juliet.