Fourth Doctor

The Fourth Doctor was something of a cross between Willy Wonka and the Mad Hatter, rarely without his signature scarf of incredible length. He was perhaps the most eccentric incarnation. After his regeneration, he seemed to be in a hurry to leave Earth, but was eventually persuaded to stay and help Brigadier Lethbridge-Stewart deal with Think Tank and the Giant Robot. But he rarely returned to UNIT during this incarnation, although he often visited Earth in the the 20th century.

He returned to Gallifrey on at least two occasions. The White Guardian sent him on a quest to locate and assemble the pieces of the Key to Time.

Struggling with the Master, he fell off the Pharos Project radio telescope down the ground hundreds of feet below. The mysterious entity known as the Watcher, which had been tracked him through time and space, then merged with him and he regenerated.