You don't actually kill him, but Eric Sparrow.
****TONY HAWK'S UNDERGROUND SPOILERS FOLLOW****
At the end of Tony Hawk's Underground, he challenges you to one last ride around your hometown, with the winner taking
the tape
.
What tape, you ask? Well, it all began in a small town in New Jersey, where you and Eric "sack of shit" Sparrow grew up and somehow managed to become friends. At that point, Eric was already an asshole, of course, but so far he was one who just had never been in the right position for his sleeze to be more than a mild nuisance. But he would soon get his chance.
See, Eric Sparrow doesn't want to be the best. He doesn't really even want to be good. He just wants to be better
than you
for no reason other than that he's a bastard-ass cockroach and you were just the only human on Earth born with the superpower of being able to put up with his shit enough to form any kind of relationship with the guy. You must have been bitten by a radioactive maggot in you sleep one night. Who the hell knows.
Whatever the reason, you cared. That was your sin.
So the easiest way Eric "if I can't have nice things, neither can you" Sparrow found to be better than you was simply to trip you up every step of the way. The little buttwipe gets you chased out of town when you get your big chance, gets you arrested, "forgets" to sign you up for the Am contest, and I must've just blocked out whatever the hell else, all because he wants you to fail at life. And like an idiot, you keep forgiving him.
Enter
the tape.
By simply being better at winning than Eric "Pissing Contest World Champ" Sparrow is at making you fail, you have astonishingly managed to get signed on with the same team as him, which decided to go to Hawaii to film the coolest/best video ever, and because you never learn from your mistakes, you give Eric "Please Kick Me in the Balls" Sparrow the camera while you film some crazy roof to roof stuff that you should really be put on suicide watch for.
Afraid of having to one-up you, Eric "Crapmaster" Sparrow attempts to talk you out of it, pretending he cares about your safety, when the cops show up in a helicopter because they
should
because you're about to get yourself killed. But you, master of all things extremely hardcore, instead decide to make the helicopter an even more over the to part of the stunt.
You pull it off, because otherwise the ending would be Eric "Bite the Hand that Feeds" Sparrow pissing on your grave, leaving Eric "King of the Buttmunches" Sparrow in possession of
the tape
that you risked your life doing the stupidest yet coolest shit you could come up with to make. And he loses it. Eric the hell Sparrow loses
the tape.
And he copies some of your less-impressive-but-still-amazing tricks to submit for the video, blowing everyone away. Because, let's face it, Eric "Petty Ass Hat" Sparrow may not have ambitions to be good, but can evidently do it if he
just has no other choice.
After getting you arrested again, this time in freaking Russia, Eric "Pain in the Ass is an Understatement" Sparrow rides the fame he stole from you to the top of the charts, with all the money and prestige that comes with it, and you sorta give up on the 'biz because as long as Eric "na na na na boo boo" Sparrow is there it's just destined to not be any fun, so you head home to Jersey and decide to just skate around, prompting literally every pro who signed an agreement with Neversoft to come knocking at your door to sign up for your new team.
But even then, Eric "Less Pleasant than Hemorrhoids" Sparrow shows up just to be a pain in the ass and let you know he won, finally inciting you to anger by presenting
the tape
, which he had all along.
Which brings us to the present. He challenges you to the contest, you accept, this is of course the game's final challenge, so you predictably kick his ass, you walk away with
the tape
while Eric "Being of Inconceivable Malice" kicks and screams in defeat.
It's a...
kind of
satisfying ending, I guess.
But on the second playthrough, while Eric "I Dashed Ya" Sparrow is inches away from your face, taunting you and trying to get you to accept his ultimate challenge, the cutscene instead ends with you wordlessly punching him right in his shit-eating-grin and walking away with
the tape.
You don't even have to do the final challenge. And it's WONDERFUL.
I have a signature now so shut up