Type 90
The Type 90 or 90-form TARDISes (PROSE: The Third Wise Man, The Book of the War) were the first generation engineered for specific military purposes. They appeared as large faceless spherical masses, and they moved gracelessly and unsubtly. Their pilots were groomed to stay neurally linked to the machinery for centuries on end, with any regeneration welding them further into the hardware. (PROSE: The Book of the War) Christine Summerfield described them as "big brass spheres" bobbing across the sky above Simia KK98, perfect cross-breeds of skin and metal from the fusion of the pilots with their ships. (PROSE: Dead Romance)
90-forms were sanctioned by the Presidency twenty years before the start of the War in Heaven. Rather than direct hostile action, their intended purpose was to block off routes through time by extending their mathematical masses into the universe's causal connections. The first few 90-forms patrolled the perimeter of Dronid's noosphere, marking out the cross-dimensional battlefield of the conflict to come, just days before the Cataclysm. (PROSE: The Book of the War)
A Type 90 TARDIS was part of the Eleventh General's strike force during the Last Great Time War. (PROSE: The Third Wise Man)
According to one account, Lady President Flavia used a Type 90 TARDIS to rescue Romana II and bring her back to Gallifrey. (PROSE: Goth Opera)