Doctor Who is streaming on Philo, AMC Plus, AMC+ and others. It's also free to watch on Hoopla and The Roku Channel. You can also buy it digitally.
The Doctor is a Time Lord: a 900 year old alien with 2 hearts, part of a gifted civilization who mastered time travel. The Doctor saves planets for a living—more of a hobby actually, and the Doctor's very, very good at it.