Well scince he hasn't shown up yet we don't know. however in the books (Which are soo much different then the tv show) they kill him with a stake from a white oak tree, they never had a dagger, there never was an elija, or doppleganger.
Wrong. Well, right, but Katherine and Elena were in the books so of course there was a doppelgänger. they both still looked the same.
Yes, Jenna dies in season 2 episode 21. Klaus kills her
yes, he does because Klaus kills him
The actor playing Klaus is Joseph Morgan. He's from London, United Kingdom.
Elijah wants to kill Klaus because he believes that after staking his siblings he through them into the ocean where they could never be found, when in reality Klaus kept his family in coffins the whole time.
He didn't die because he isn't full vampire anymore he's half werewolf so the dagger does not apply (If a vampire uses the weapon on another vampire they both die) An original can't be killed so easily, only the wood from a certain tree can kill an original. The ashes that Klaus dips the dagger in only netralize his siblings. Since Klause is a hybrid the dagger and ash do not apply to him.
Klaus Abramowsky died in 1998.
Fred Klaus died in 2005.
Klaus Woerner died in 2005.
Klaus Höhne died in 2006.
Klaus Holzkamp died in 1995.
Klaus Störtebeker died in 1401.
Klaus Dittrich died in 2007.
Klaus Scholder died in 1985.
Klaus Winter died in 2000.
Klaus Riedel died in 1944.
Klaus Löwitsch died in 2002.
Klaus Egge died in 1979.