Dr Who is a British sci fi series about a man simply called "The Doctor", who is the last of his race of Time Lords. He travels space and time in a blue 50s-era British police box, usually accompanied by a woman.
The program originally ran from 1963 to 1989, and was revived in 2005. There have been several actors playing the Doctor, something explained by the Time Lords ability to regenerate several times over their lifespan. It allows them to cheat death, but they look different and have slight personality changes as a result.
I was originally introduced to the Doctor by my roommate/best friend, and since then my brother and his best friend have all caught up on the show.
The effects are often cheesy, the acting hit and miss, but the themes are powerful. The show as a whole is at once powerful, intelligent, comedic, insightful, exciting, and heart-wrenching.
Highly recommended viewing!