The 3rd Doctor needed to regenerate as a result of radiation posioning from defeating The Great One on Metebelis 3.
He regenerated into The 4th Doctor, as played by Tom Baker.
Below is a complete list of The
4th Doctor adventures.
Click on each episode to find out more, including Cast and Crew lists, Synopsis', Merchandise information, as well and
pictures and other related media. There are also options to discuss and review each episode by clicking on the interact buttons.