Top hat
A top hat was a type of hat.
The Eleventh Doctor owned a top hat, which he wore at Amy and Rory's wedding, (TV: The Big Bang) after having been poisoned by River Song in Nazi Germany (TV: Let's Kill Hitler) and again to conceal a device that allowed him to lure the Squall back into their dimension of origin. (PROSE: Paradox Lost) During his retirement to the Victorian era, the Doctor wore a battered felt top hat, a burgundy frock coat, a waistcoat with collars and a pocket watch with a fob chain. (TV: The Great Detective, The Snowmen)
The Twelfth Doctor wore a navy blue top hat which he soon gave to a little girl and switched for a black one during a visit to the 1814 frost fair. (TV: Thin Ice)
Occasionally, the Eighth Doctor wore a top hat, (COMIC: The Curious Tale of Spring-Heeled Jack; AUDIO: Other Lives)
Ryan Sinclair and Graham O'Brien wore top hats during their visit to Villa Diodati duirng 1816. (TV: The Haunting of Villa Diodati).
The Master during his spy incarnation wore a top hat when he confronted the Thirteenth Doctor on London during 1834. (TV: Spyfall)
Walter Simeon wore a top hat, (TV: The Snowmen) as did the Great Intelligence using his form as an avatar. (TV: The Name of the Doctor)
The Pied Piper, posing as Elijah Spellman, wore a top hat with his ringmaster costume. (TV: The Day of the Clown)