One of the cooler characters in Star Wars
You first see him in A New Hope, now episode 4. He boards the ship, wearing all black, and with a black samurai helmet and mask and sounds of a respirator. His voice is very deep, that of James Earl Jones. He is strong enough to pick up the captain, choke him, and throw him in search for the Death Star's stolen schematics. The nice thing about that movie is that you can figure out what's going on in the first few minutes. I'm not going to spoil anything in next few paragraphs, so you can read them.
He is very powerful, and can use The Force. He can raise his hand out, and move things through the air using The Force. However, he is on the Dark Side, using the Force for evil means. He chokes people with it from across the room, even as far away as other spaceships. It augments his senses, he can sense his old master Obi-Wan Kenobi nearby.
Ob-Wan Kenobi and Luke Skywalker's father Anakin fought together in The Clone Wars. Darth Vader eventually betrayed Luke's father and killed him.
According to the Star Wars mythology and from some of the dialogue, Darth Vader was Obi-Wan's apprentice once. When Vader went over to the Dark Side, they had a lightsaber battle. Vader got seriously wounded, so badly that he needs the suit and respirator to survive. This isn't in the movie, so we only see the final showdown between them, which I don't want to say how it ends.
Creator George Lucas says he expects people to eventually watch the movies in episode order 1-9. Until episode 3 comes out, I'd reccomend seeing the movies in episode order 4,5,6,1,2,3. That way you are suprised by some of the enormous character twists in The Empire Strikes Back. More on that later in the Spoilers.
Lucas said that the entire story is told from the point of the droids. I disagree. In episodes 4,5, and 6, that could be true, or the story can focus on Luke. With the newer episodes, I'd say that the entire series evolves around Vader, and his journey to the Dark Side. Perhaps Lucas agrees with me, he said the series is all about Anakin as "a fallen hero." One astute film critic pointed out how it's symbolic of the angel Lucifer's fall from heaven.
Cool fact, "Vader" is Dutch for Father. I imagine that at the Dutch screening of The Empire Strikes Back, there wasn't as much of a suprise over how the plot went.
Spoiler(for A New Hope)- Vader is the only bad guy who actually escapes the Death Star alive.
Spoiler(for The Empire Strikes Back)- Vader fights Luke Skywalker in a Lightsaber duel. Luke gets his hand cut off. He's holding onto the edge with one hand, and Vader makes him an offer to join him in conquering the Universe.
Luke:"I'll never join you! You killed my father!"
Vader:"No, Luke...I am your father."
Spoiler(for Return of the Jedi)- Luke must face his father again, to save the Universe. It's his destiny and he can't run from it. Luke believes he can turn his father back from the Dark side...and he succeeds. Vader dies soon after, but thankful to Luke for saving him from the Dark Side.
Spoiler(for The Phantom Menace)- We go back to the absolute beginning of the series. Obi-Wan kenobi meets Anakin Skywalker. He's a slave on the planet Tattoine. His mother is a slave, and he doesn't seem to have a father. He has the highest midichlorians count in his blood ever, higher even than Yoda, meaning the Force is extremely strong around him. The Jedi Qui-gon Jinn believes that since he senses a vergence in the Force centered around Anakin, he could have been conceived by the Force itself.(A Jesus reference?) Could he be the prophesized One who brings balance to the Force? Obi-Wan takes him as an apprentice.
Spoiler(for Attack of the Clones)- 10 years later he's still an apprentice. The Force is strong with him, but he still has feelings of anger, lust, and love. A Jedi shouldn't have these things, but it shows that he is starting to stray from the good Side. His mother dies, which causes him to slaughter all the Tuscans he could find. He falls in love and marries Amidala. He's angry at Obi-Wan Kenobi. Also, he lost his hand.
What can we expect in Episode 3?
Anakin's anger might be enough to move him completely to the Dark Side. See Things that MUST happen in Episodes 2 and 3 for more speculation.
I expect to see more of Anakin vs Obi-Wan. They first meet in Episode 1:The Phantom Menace. In Attack of the Clones, Vader is Obi-Wan's apprentice, 10 years later, but there's a rift forming between them. It's very likely that we'll see them battle in Episode 3. They face off in Episode 4 for the last time.