Pagliacci was an opera written by Ruggiero Leoncavallo in the late 19th century on Earth.
Pagliacci was one of the operas being played at the Dorothy Chandler Pavilion, Los Angeles in 1996. (VOY: "Future's End, Part II")
For his first performance on the Qomar homeworld in 2376, The Doctor reproduced the backdrop of a production of Pagliacci at the Teatro alla Scala. (VOY: "Virtuoso")