Who is Darth Vader's father?

In the movies, we are led to believe that Anakin Skywalker (Darth Vader's original persona), was the product of a virgin birth and seemed to have no biological father. This seems to be the main reason that Obi Wan felt he was the chosen one.

However, it is implied that The Emperor's (a/k/a Darth Sidious', Senator Palpatine's) predecessor - Darth Plagueis - used his powers of the Dark side of the force to manipulate the Midichlorians to to conceive Anakin. That is how Anakin came to be.