Darth Vader. Galactic Villain. Servant of the Dark Side.
Despite his many flaws and wrongdoings that cast the galaxy in darkness, he did it all for one ultimate purpose. Family.
He turned to Palpatine for guidance when he learnt that Padme could die, and he would lose all of his family, including his unborn children. He sought to find that higher, but forbidden, power to stop her from dying.
When he met Luke on Cloud City, he promised to rule the galaxy as father and son. He wanted a sense of belonging once again. He wanted power to finally protect the family he had failed those years ago.
On the second Death Star, he knew that to save his children, he has to give up his life. The ultimate sacrifice to ensure the safety of his children from the Emperor. He knew he, as Vader, has to die so that he can once again be brought back to the light side, to be a Skywalker again.
Darth Vader, may not be the perfect moral character in Star Wars, but he undoubtedly wins Father-of-the-Galaxy.