It's fun to figure out what archetypes, cliches, and tropes that characters can fit into. It's more fun when the series is less known and there aren't eighty million, because, you know formatting can be a hassle. On the other hand, Xanxus never makes anyone's life easy!
The Alcoholic: A fan book claimed that he likes tequila and whiskey, and seen holding some type of liquor in some instances. A lot of art pictures and stuff show him holding liquor of some sort. One particular scene in the anime has him drinking red wine (looks like it) but we never actually see him drink it. More likely, he destroys the glass or throws it at Squalo.
Angrish: Basically his entire dialogue is insults and angry swearing. I'm not certain I've ever heard him say anything remotely nice or neutral.
Art Evolution: His appearance went from sharp to much softer (his hair for instance). He seems more laid back, but actually has the same temper.
Authority Equals Asskicking: Actually it doesn't, but he's the leader of an elite assassin squad, so who am I to argue? Really, he does kick a lot of ass.
Badass: He has two guns, he can fly, and he is almost completely capable of doing anything. Also, look how cool he looks!
Bad Boss: He's physically and emotionally abusive to his subordinates and they still stick around. They would follow him to hell and back.
Beauty Is Never Tarnished: Let's face it, chicks dig scars and glory lasts forever.
Beam Spam: His x-guns have two modes. Shoot and shoot beams.
Berserk Button: It's not so much of a button as a switch that doesn't turn off? When angered there's no calming him down. Best thing to do, keep your mouth shut.
Big Bad Good: Xanxus is the catalyst for Tsuna having to be the Tenth Boss. On the other hand, after his defeat he supports the family in his own way.
Big Eater: Much of Xanxus' temper tantrums happen over food. And how they're wrong. A master of table flips, I feel like he wastes more time with tantrums than actually eating.
Bring It: Xanxus gets bored quickly. While fighting Bel's brother, Rasiel, he frequently yawns, tells the kid to bring it, then proceeds to beat his ass.
Coat Cape: He doesn't wear a coat, it's a cape. It looks like a coat, but it's not. (It is. I don't know, science doesn't apply to Xanxus.)
Cool Chair: He has a throne like chair that he's always sitting in. I bet he makes the Varia carry it around.
Determinator: I covered this in he's here because he's never lost.
Deep Sleep: He spent eight years frozen. Some speculate that this kept him mentally the age that he was frozen. Which I feel is better than him being aware of everything. At the same time, I also feel it helps explain some of his mentality.
Don't You Dare Pity Me!: Ever. No one feels sorry for Xanxus. You do? Have a bullet to the face!
Energy Ball: The Flame of Rage. Every time, just stop talking and he'll stop destroying things.
Even the Guys Want Him: His men love him despite his abusive behavior. They seriously live to make him happy. I feel bad for the poor sap that has to explain that nothing makes Xanxus happy.
Everyone Has Standards: He hates Tsuna. With every fiber of his being. But he lives for the Vongola.
Xanxus: "Regardless of our internal strife, in times of crisis, when we are attacked by scumbags from the outside... We, the Vongola, are always... as one!!"
Evil Counterpart: Xanxus is Tsuna's complete opposite. Looks, personality, life goals, upbringing, you know, everything.
Evil Laugh: He has an evil laugh that he uses frequently. Usually when one of his men gets killed beat. Or when he's overly amused about how trash tries to stop him.
Evil Sounds Deep: Deep, manly, and raspy. (And oddly calming.)
Female Gaze: In the anime, during his fight with Rasiel, the camera spends quite a bit of time lingering on those leather-clad legs of his. Can I also mention a lot of manga images also have him shirtless? Just sayin'.
Gangsta Style: Can I hold my gun sideways?!
Generation Xerox: Basically, he's a carbon copy of Ricardo that actually has no ties to the Vongola Family (much to his dismay).
Good Scars, Evil Scars: We covered scars already, right?
Guns Akimbo: Special two hand guns, my favorite!
The Gunslinger: A very skilled shooter he can hit anything and everything, but usually defaults to vaporizing everything.
Hair Decorations: Xanxus has some colorful feathers and a raccoon tail tied to his hair. Because he's not dumb enough to make a promise on hair like some people (shh, Squalo, so am I)!
Human Popsicle: Frozen by Zero-Point Breakthrough for eight years.
Jerkass: A spoiled brat who believes the world owes him something because he's superior in every way. He's certainly not pleasant.
Older than They Look/Younger than They Look: Xanxus is mentally younger than he looks. I would say at 16 he looked older than that but being frozen didn't help his mind any.
Ominous Pipe Organ: His theme music. It is awesome. And relaxing. I don't know why.
Orcus on His Throne: He is usually sitting. During the Ring battle with Tsuna he gets out of the chair. In his battle with Rasiel, he fights the entire thing from his mini-throne.
Perpetual Frowner: His smile is a little more akin to a cat's; it might be nice to see until you see it.
Person of Mass Destruction Do I need to elaborate on this?
Pet the Dog: He does acknowledge that Tsuna is best for keeping the Vongola at its strongest.
Pyrrhic Villainy: After his defeat at Tsuna's hands he takes the rings by force. The rings reject him making the whole ring battle pointless because he'd never be able to use them anwyays.
Rage Against the Mentor and Calling the Old Man Out: After finding out about the fact that he's adopted he decides to bring down his father and the family.
Real Men Eat Meat: Likes steak but is very picky about it. Usually causes a temper tantrum.
Red Eyes, Take Warning: Rasiel mentions that he as the eyes to match Bester.
Scars Are Forever: Xanxus' appear when berserk mode activates!
Shirtless Scene: So, basically chapter covers; but you know I don't blame Amano. It may or may not be the reason I'm a fan.
Significant Anagram/Sdrawkcab Name: To the theme of being Tsuna's polar opposite, if the X's are removed and his name is spelled backwards, the phonic pronunciation of the kanji "Suna" means "sand or grit" to signify the deterioration of structures in the passage of time. In contrast to "Tsuna" meaning "rope or bond" in recreating relations in the Vongola (TV Tropes).
The Slacker: Xanxus prefers to let everyone else work. He'll wait in his comfy chair. WHen he does decide to get serious, beware.
Slasher Smile: Kind of like a smile but not any we'd recognize.
Slouch of Villainy: He's too bored to even sit up to fight you. Deal with it.
Social Darwinist: The strongest will survive, trash can show itself out.
Spoiled Brat: Raised in the strongest family to be its next boss. Throws temper tantrums when he doesn't get what he wants. Believes he's God's gift to the world. Might be a touch spoiled.
The Stoic: He has three facial expressions. No expression, uncontrolled laughter, and pissed.
Tall, Dark and Handsome: And how!
Team Dad: The disciplinarian of the group. Everyone lives by his rules. Lussuria thinks of him as the dad of the varia and I'm not sure how to feel about it!
This Cannot Be!: When he loses, it can't be possible. Despite being outmatched by Tsuna, Xanxus still believes he's superior in every way.
Unusual Eyebrows: His eyebrows actually split into two.
We Have Reserves: He doesn't have time to waste on dead subordinates. They have spares. Point in case, he came unglued with laughter when Squalo lost and became shark bait. In the Ten Years Later Arc when Squalo was thought dead he seemed almost relieved by the idea. So, long story short, he.doesn't.care.