The Monk's TARDIS

The Monk's TARDIS was a Mark IV TARDIS owned by the Monk.

History
Unlike the First Doctor's TARDIS, at this time the Monk's TARDIS had a functional chameleon circuit and directional unit. After visiting several moments in Earth history, he landed in 1066 Northumbria and disguised his ship as a stone sarcophagus in his monastery. The Doctor learned of the Monk's plans to change history and sabotaged his TARDIS, making it the same size inside as outside. This made it impossible for the Monk to get inside it. (DW: The Time Meddler')

The Monk eventually fixed the dimensional controls. On a later adventure on the volcano planet Tigus, Mortimus's ship turned into a large rock. Meeting again in ancient Egypt, the First Doctor changed it into a police box so Mavic Chen and the Daleks would mistake it for the Doctor's TARDIS. He also stole the Monk's dimensional controls so the Monk would re-materialise in a random location. The Monk ended up in an frigid planet with his TARDIS disguised as a block of ice. (DW: The Daleks' Master Plan).

When the Fifth Doctor next encountered the Monk, he had voluntarily re-configured his TARDIS into a police box. The Monk had the top of his ship's roof blown off by Ice Warriors with a sonic cannon. (DWM: 4-Dimensional Vistas)

The Seventh Doctor met the Monk in 1976 London. Mortimus, posing as a record executive, had turned his ship into a desk, complete with scraps of paper. The papers retained some of the special qualities of his TARDIS, allowing the Doctor to use them to return to Earth after the Monk vengefully tried to abandon him on the same icy planet where he had been trapped. (NA: No Future)