Giacomo Puccini

Giacomo Puccini (1858-1924) was an Italian composer.

Dr. Grace Holloway was a fan of Puccini, and listened to his opera Madame Butterfly while she performed surgery on the Doctor which caused him to regenerate. Later, the amnesiac Doctor hummed the music to himself, and upon seeing Grace it jogged his memory. Seeing Grace's CD of Puccini's music further jogged the Doctor's memory of being with Puccini before he died, and of Franco Alfano finishing Puccini's opera Turandot based on his notes. (DW: Doctor Who)

Some time before those events, the Doctor had found himself trapped in a decompressing airlock as Madame Butterfly played, and was determined not to die to the sound of what he dismissively called "elevator music." (BFA: The Death Collectors)

The Eighth Doctor locked a prison known as "the Cube" with a complex cryptographic seal, the password to which included a Puccini aria played backward. (BFA: Something Inside)