Doctor Who and The Ghost of Time.

After receiving a call from Kate Lethbridge-Stewart, the Doctor returns to UNIT to investigate a mysterious package addressed to him. When he sees what's inside, he races back to the TARDIS, only to be haunted by a chilling warning: the Ghost of Time is coming for him.

With the fabric of reality at stake, the Doctor must face his past and uncover the secrets of his own existence.

This is a story I would write as a new showrunner to fix the timeline and recapture the ideas of forgotten stories: the Valeyard, the Shalka Doctor, and the Dark Dimension itself.