His name is practically synonymous with the wise, prudent teacher, who guides the hero along the True Path of Good.
This is odd, because Obi-Wan Kenobi is a huge douche.
The popular duel on Mustafar between Anakin and Obi-Wan provides a good example of why (yes, we'll have to wade through the awful dialogue):
Obi-Wan: "You have allowed this Dark Lord to twist your mind until now you have become the very thing you swore to destroy."
Anakin: "Don't lecture me, Obi-Wan. I see through the lies of the Jedi. I do not fear the Dark Side as you do. I have brought peace, freedom, justice, and security to my new empire."
Obi-Wan: "Your new empire?"
Anakin: "Don't make me kill you."
Obi-Wan: "Anakin my allegiance is to the Republic, to democracy!"
I have a problem with Obi-Wan's last sentence there. You see, Palpatine didn't enact a coup against the Senate, he didn't start a revolution, he was duly elected, both as Chancellor, and then as Emperor. It was the democracy of the Senate that put Palpatine in power. Now, some of you will point out that Palpatine may or may not have used his Sith mind tricks to win the Senate over. OK, but how is that qualitatively different than what any real-world politician does to get elected? In fact, wouldn't democracy be really vulnerable to the mind-control powers of the Sith? Wouldn't all the successful politicians be Dark-Side force sensitive (Jedi being barred from politics)? So Palpatine didn't destroy the democracy of the Republic (in fact, he does not dissolve the Senate for another 20 years or so), he was the product of it. If the Jedi are really the defenders of the Republic, then they should have stepped aside to make way for Palpatine's rise to power.
Instead, the Jedi react as any group of humans does when an enemy group takes power (or in this case, when they discover that the seat of power is a member of an enemy group): they go outside the rules to try to win. The Jedi dispatch a squad of assassins to eliminate the duly-elected Chancellor in what can most charitably be called a coup attempt. Palpatine, having graciously allowed his enemies the first move, kills them all anyway, except for Anakin, whom he converts to his side. In response to the attempt on his life, Chancellor Palpatine makes his move, securing his power further in yet another completely legal vote, resulting in his coronation as Emperor. Meanwhile, he excises the rest of the Jedi, which is perfectly understandable, because, as you might have noticed, they are exceptionally dangerous. Obi-Wan and Yoda aren't calling it quits, though, and make yet another assassination attempt on the legitimate head of state, which fails.
So Obi-Wan is a hypocrite, claiming to be a defender of democracy, but in fact being an enemy of it. That reminds me of someone else.
Later in the scene, we see Obi-Wan confess his failure to Anakin as a mentor. Here's the transcript:
Obi-Wan: "I have failed you, Anakin. I have failed you."
Anakin: "I should have know the Jedi were plotting to take over."
Obi-Wan: "Anakin, Chancellor Palpatine is evil!"
Anakin: "From my point of view, the Jedi are evil!"
Obi-Wan: "Well then you are lost!"
Wait just a freaking second. What was it Obi-Wan was saying just five minutes earlier?
Anakin: "If you're not with me, then you're my enemy."
Obi-Wan: "Only a Sith deals in absolutes. I will do what I must."
In fact, everything Anakin says here is demonstrably true. The Jedi made not one, but two assassination attempts on the legitimate head of state. The Jedi routinely interfere in affairs outside their jurisdiction. The Jedi undermine the system that they are sworn to protect. Q.E.D., evil.
Fast forward twenty years, and we see that Obi-Wan has absolutely no problems lying to his newest apprentice if it means he will unquestioningly follow Obi-Wan's version of events. In fact, here's a montage of Obi-Wan lying, and here's a Robot Chicken musical number about the deceptions of the Jedi. This has more or less been beaten into the ground, so I don't feel like going over it again.