Malcassairo
Malcassairo was one of the last outpost of humanity at the last year of the Universe in the year 100,000,000,000,000.
Malcassairo was mostly covered in dead scrub land and hills, with the only artificial features being the Malmooth Conglomeration, which was later deserted with the extinction of the Malmooth, a basic Futurekind camp, and Silo 16, a Silo where the last remnants of humanity gathered and later left for Utopia.
In 100,000,000,000,000, the Doctor, Martha Jones and Jack Harkness arrived on the planet after the TARDIS flew to the end of the universe in order to try and shake Harkness off. The travellers assisted the elderly Professor Yana in the attempt to send the humans in a rocket to Utopia. However, Martha alerted Yana to his fob watch, in reality part of a Chameleon Arch containing the Time Lord essence of the Master, who had taken human form as Yana. Yana opened the watch and reverted to his Time Lord form. He killed Yana's assistant, Chantho, the last surviving Malmooth, and regenerated in the TARDIS after being fatally wounded by Chantho. The Master then abandoned the three time travellers on Malcassairo (DW: Utopia), travelling to 21st century Earth. The travellers escaped using Jack Harkness' vortex manipulator. (DW: The Sound of Drums)
Following the Master's death on board the Valiant, the Doctor cremated his body in a place which resembled Malcassairo, although it was never stated to be this planet. After the Doctor had left, an unidentified hand took the Master's ring from the pyre, with the Master's laughter audible. (DW: Last of the Time Lords)
