Operas were a form of musical plays.
The Doctor met opera singer Nellie Melba. (TV: The Power of Kroll)
Romana once dragged the Doctor to an opera in Milan. (PROSE: The Scarlet Empress)
The opera Il Dottore Va in Viaggio was a dramatisation of one of the Doctor's adventures. (PROSE: Transit)
Grace Holloway was a fan of opera, particularly Madame Butterfly. (TV: Doctor Who)
During a visit to London in 1840, the Eighth Doctor hoped to attend the opera Les Huguenots, but it was sold out. (COMIC: The Curious Tale of Spring-Heeled Jack)
The Eighth Doctor took Sam Jones to an opera performed by silicon-based life-forms on Thurakzima 7. She later listened to the Doctor's recording of Aida while they were travelling to its inaugural performance in Egypt in 1871. (PROSE: The Janus Conjunction)
The Eleventh Doctor and Amy Pond attended an opera in Paris in 1858, where they met opera singer Cosette. (COMIC: The Screams of Death)
Ultragrossegotterdamerung was an opera, performances of which lasted for over a month. (COMIC: Space Vikings!)
Oswin Oswald was a fan of opera, particularly Carmen. (TV: Asylum of the Daleks)
The March of the Cyborgs was an Agoran opera. (PROSE: UNIT Christmas Parties: First Christmas)
Operas were common at the Intergalactic Fringe Festival. During the visit of the Twelfth Doctor and Bill Potts, operas were performed by a group of Judoon and by a rock. While the Doctor was excited to see the rock's rock opera, telling Bill it was considered a "real gem," he called the Judoon's opera a "no-go show". (AUDIO: War Stories)