The TARDIS is a rare constant in Doctor Who, a series that is constantly changing. The design of the TARDIS control room may undergo occasional changes and the police box exterior has been slightly remodeled from time to time, but ever since Doctor Who began in 1963, the image of a police box traveling through time and space has been at the heart of the sci-fi series. However, the Doctor’s TARDIS -- an outdated Type 40 -- isn’t the only TARDIS that has appeared on Doctor Who. Throughout the Doctor’s travels, they have occasionally met other wandering Time Lords, stumbled across abandoned TARDISes, and uncovered other species’ efforts at replicating the TARDIS.
Source：https://www.cbr.com/doctor-who-tardis-master-rani-monk/
