Beauty Equals Goodness: The most handsome man just happens to be "The Good". Granted, the other two were morally worse than him, but Blondie's not exactly a nice guy.
Beware the Quiet Ones: Blondie is capable of being as violent and ruthless as Tuco, but he's much less flamboyant. He barely ever talks above a whisper, and he frequently confronts life-threatening situations without uttering a single word. Even when he's crawling through the desert, half-dead from sunburns and dehydration, he never once begs Tuco for his life.
Bounty Hunter: Though, he has a tendency to claim bounties and free said criminals, raising the bounty and turning them in at another town to make more money.
Genre Savvy: Unloading Tuco's gun the night before the showdown did the trick.
Good Is Not Nice: An odd case where he's soft-spoken and rather polite, but acts like as much of a scoundrel as Tuco or Angel Eyes. However, he still retains a moral value unlike the other two and most of the time does what's right, as long as it doesn't interfere with going after the gold.
Bond One-Liner: "When you have to shoot, shoot, don't talk." Actually improvised on the spot by Eli Wallach.
Butt Monkey / The Chew Toy: He isn't successful for more than 20 onscreen minutes. Although, considering that Tuco is a scheming and opportunistic bandit, he probably deserves most of what happens to him.
Eye Scream: Wallace gets him to reveal to Angel Eyes the name of the cemetery where the gold is buried by pressing down on Tuco's eyes with his thumbs.
Faux Affably Villainous: When he's taunting Blondie, he speaks in a reserved, cool manner (that is, until Blondie pisses him off). Regardless, Blondie himself isn't fooled, and is never really intimidated by Tuco. Except for the two occasions in which Tuco actually comes close to killing him.
Genre Savvy: Enough to hide a gun under the bubbles when he takes a bath. It works, too.
Gold Fever: One could argue that Tuco has it the worst. Just watch his "Gold Ecstasy" when he finally digs up the treasure during the finale.
Hair-Trigger Temper: When Blondie rescues him the first time, they're both laughing about it like old friends. Then, in the next scene, he's screaming countless obscenities as Blondie prepares to turn him in for the bounty.
I'll Kill You!: After he is left behind in the desert when Blondie dissolves their initial partnership.
Jerk with a Heart of Gold: The more we get to know about Tuco, the more we understand that he's one of these. Justified since Tuco is the only character whose backstory we learn; Blondie's and Angel Eyes' histories are a complete mystery.
Made of Iron: Gets hit full-on by a blast of cannon fire, has the hell beat out of him by Wallace, jumps out of a moving train and down a pretty steep hill, and is nearly hanged for his crimes on several occasions.
Nice Hat: For a good portion of the movie, although he loses it following the episode in the second Union camp.
Nice, Mean and In-between: The Inbetween. Obviously, one is "The Good", the other is "The Bad", so "The Ugly" is inbetween by default.
No-Holds-Barred Beatdown: Receives an extremely painful one from Wallace. He gets his revenge after springing from the POW train and breaking Wallace's neck, after which Tuco proceeds to savagely beat his head with a rock.
Obfuscating Stupidity: He acts pretty buffoonish and has some genuine moments of stupidity, but that doesn't mean he's not dangerous. Not at all.
Oh, Crap: Has three moments: the first when he realizes the true colors of the soldiers whom he has mistaken for Confederates, the second when he notices that Blondie has set up a hangman's noose for him in the cemetery, and the third is his reaction when he thinks Blondie is going to shoot him rather than cut the noose.
Pet the Dog: After punching his brother due to his "The Reason You Suck" Speech and walking out on him, Tuco notes that no matter how low he sinks, he'll always be the one man who'll offer him a free bowl of soup.
Real Men Wear Pink: At one point carries a shredded pink parasol to shield himself from the sun (as well as taunt Blondie, who is crawling through the desert on his hands and knees).
Dumb Muscle: Letting a scheming, conniving bandit out of his sight for even a minute onboard a moving train probably wasn't a good idea.
Jerkass: Unlike Angel Eyes, he had no inner motivation for what he did, and mercilessly pummeled Tuco simply because Angel Eyes told him to.
Mutilation Conga: After inflicting a cold-blooded beat down on Tuco (courtesy of Angel Eyes), Tuco makes his escape by pushing Wallace out of a moving train (which either knocks Wallace out cold or kills him instantly), and then Tuco proceeds to bash his former captor's head in with a rock. As if that wasn't enough, Tuco frees himself from a set of handcuffs by placing Wallace's body on the train tracks, which not only breaks the link on the cuffs, but takes Wallace's body with it.
Sociopathic Soldier: Does torturing prisoners for information not in any way related to the War at hand count? Check.
Torture Technician: Gets medieval on Tuco's ass by attempting to squeeze out the latter's eyes with his fingers.