Seventh Doctor's regeneration
From Tardis Wiki, the free Doctor Who reference
The Seventh Doctor underwent his regeneration into the Eighth Doctor in Walker General Hospital on 31 December 1999. Following a non-fatal shooting, the Doctor had been taken to the hospital where subsequent exploratory surgery by Grace Holloway with a camera accidentally clogged a vein; the anaesthetic he had been given delayed the regeneration by several hours almost destroyed the process entirely. (TV: Doctor Who) This was the seventh regeneration of the 12-regeneration life cycle beginning with the First Doctor. (TV: The Time of the Doctor)