Alright. Spies are the class with the most side classes in the game, and they also have the most noticable change between stages of skill. This guide will cover each type of spy, defining characteristics, advantages, disadvantages, and how to beat them. 95% of you readers have probably had a few problems with at least one of these types, so enjoy your revenge.

Yep. We've all seen this guy.

So, let's start from the beginning. Baby spies are on their first or second game as a spy, and they have no clue what they're doing.

Characteristics:
1. Hatless
2. Random
3. hangs near other players (either team)
4. Very confused attitude.

Advantages: These guys are just learning what the buttons do, so they may be highly unpredictable. They may randomly cloak for no reason, sap a sentry and just stand there gaping, or attempt a backstab on a pyro from the front. They're confused, but they're also confusing.

Disadvantages: They've got nothing but their randomness going for them. They don't yet understand who to target/stay away from, good hiding spots on the map, or why their teammates are shooting them (spychecking). He sometimes shoots spychecking friends until he's out of bullets. He also doesn't really know how disguises and cloak works yet.

How to beat them: Just let their ignorance do the work for you.

Side classes:

Newborn Spy: These guys follow teammates (usually other spies) around and try to imitate them. They will also ask other teammates how to get the weapon the teammate has.

Look gaiz, i haz a hat!

The name coined by Jerma985 (i think), these guys are the next step up the chain. Shpees still have no clue what they're supposed to be doing, but they've singled out one player enough or gotten lucky enough to get a domination. They do understand game mechanics, though. Now, I do not think that hats=skill, but this is the only hat these guys have, and they wear it proudly.

Defining characteristics:
1. Gibus
2. Basic idea of the game and tactics
3. Random behavior

Advantages: These guys know that a backstab is insta-kill and sappers wreck engi buildings. That's about all they know, but they make the most of it. These guys may have a modded loadout, but they generally just stab the nearest person.

Disadvantages: They're jittery and unaware. If enemies see a pyro with the Powerjack running towards a sentry shouting "Go Go Go", they know it's a shpee. They also tend to run at odd angles and jump just for the fun of it. If the shpee's team doesn't have any actively shooting snipers, It's definitely suspicious.

How to beat them: Look for telltale signs. Or for snipers, use the razorback. These guys don't know enough yet to shoot you.

Sentry over there? Watch me be epic.

These guys sometimes... They all want to be as impressive as possible. They chainstab, tauntkill, Y.E.R. stab, Ambassador headshot, and get into sapping wars with engis. They are the most predictable, yet frustratingly hard to stop, of all of the spy classes. However, they do finally understand what to do and how to do it.

Characteristics:
1. Extremely careless, they will do anything for just...one...more...stab...
2. Modded loadout
3. Few/no hats
4. Slightly useful, but not great

Advantages: They understand how TF2 works, and they use every tool in their arsenal to do whatever they can (and really annoy their enemies).

Disadvantages: They're not really that stealthy. They charge at players and sentries, and generally showboat.

How to beat them: They will eventually stand still and become target practice (taunting, typing in chat to laugh at the enemy, etc.), but they will generally try butterknife charging any player that notices them. Combine that with a well-guarded sentry or aware pyro and goodbye spy.

This is where this path becomes a tree and not a chain. Spies generally spend their next hundred hours or so of gameplay doing two things: aquiring hats and training with one weapon or another. Each spy is different, but these are generally what they do.

Practice:
With knife? They're a stairstabber.

With gun/sapper? They're a Weapons Pro spy.

Being annoying? They're a troll spy or one of it's sub-classes.

With cloak/disguise kit? They're Stealthy spy.

A mixture? They're Creative spy.

Bam! Did ya see that?

Stairstabber spies live up to their name very well. They don't select targets and kill them. They select targets, annoy them for about 30 seconds, then kill them in some amazing trickstab. Much like the teenager spies, these guys crave attention, and will not accept a plain kill unless they are in serious danger. Every revenge against them is a personal insult, too.

Characteristics:
1. Arrogant
2. REALLY good with the knife
3. Very quick to reverse a revenge.

Advantages: Even rage pyros can't beat this guy. He will backstab you with your back in a corner while you are surrounded by M1 pyros. If you're his target, he WILL kill you.

Disadvantages: he has two main weaknesses. He's both impatient and predictable. He's going to backstab you, yes, but in the same way he has the last 15 times.

How to beat him: Keep your cool. The only reason rage pyros can't beat him is because they're as intent on killing him as he is on killing them. He catches you off-guard a few times, and by the time you've learned your lesson, you're so mad you go rage pyro just to kill him. Keep cool, slow down near stairs and ramps, and he will miss the stairstab and he will instead land right in front of you.

Spy Version 2.0: Now with ranged weapons!

Weapons Pro spies leave nothing to the chance of a random backstab. They use every tool in their arsenal to full effect, when the time is right. However, they don't have very much situational awareness. They tend to headshot an engineer without sapping the sentry first. They're kind of dumb, but they can definitely outwit opponents looking for them.

Characteristics:
1. Use all of their weapons
2. Knows when to fight and when not to
3. Lack situational awareness

Advantages: These guys don't rely on close range combat, so it's harder for pyros to kill them. They're also pretty good headshotters, so snipers beware.

Disadvantages: Again, sentries or sneaky pyros can easily take care of this guy, as he tries to get the first kill he sees.

How to beat him: Spycheck, or use scout/powerjack pyro. If he can't outrun you, he's doomed.

Sub-classes:

Sapper Spy:
These guys may also fall under Troll spy, but they belong here more. They sap a building, cloak and run while the engie repairs it, and repeat. They usually use the Red-Tape Recorder and the C&D.

Advantages: They are very stealthy until they get to the sentry, usually perma-cloaking.

Disadvantages: They stick around one area and harass the same engi over and over.

How o beat them: Locate your sentry near where your team hangs out (frontline dispenser, spawn, etc.), or recruit a pybro. These guys don't really care about enemy players that much.

That's "Need a dispenser here", by the way.

Troll spies have so many sub-classes, but I'll only cover a few. To sum these guys up: Useless and annoying. If you see one, you might want to switch servers/teams.

Spycrab:
These guys are endangered, and harmless. They crouch, hold their disguise kit, look up, and walk around. You don't need to know their stats because they don't actually do anything.

Scumcrab:
The older, nastier cousins of the spycrab, these guys spycrab for about 15 minutes (or until they gain the other team's trust). Then, as an enemy passes them, they stand up and backstab him. After a backstab, they cloak, move to a different location, and repeat the process.

How to beat them: Stand near a sentry or keep your eyes on the spycrab at all times.

Spammer spy:
Like the guy above, these guys just spam an annoying message over and over. They're still harmless, but they are really aggravating. They could also use the C&D to troll or spam L with the intelligence (only works in pairs).

Fake sphee:
These guys put the gibus on and act confused. They just wander randomly around the map, spam voice commands, and act like a noob. Then they get a chainstab. These guys are annoying to the extreme.

Tele camp spy: (suggested by SapperPlanter)
They tend to hang around teles with the YER, and depending on the stupidity of the enemies, can rack up kills.

Advantages: Can help hold a point when defending for much longer due to the fact anyone using a tele is killed. As well as making the tele useless, they kill anyone who uses one, reducing the amount of attackers.

Disadvantages: Tend to leave high value targets, sentries and dispensers alone for unsuspecting tele users. They also never sap teles, even if they'd do alot better for their team in doing so.

How to kill them: Round up your team and walk to your tele exit. He won't expect a thing, because he will be too busy staring at a tele. As an engineer, it is your duty to move a tele porter exit when a tele camp spy is haning around it, to prevent it becoming a gallow for your team. It can be fun to use the rescue ranger to troll these guys.

Suprise!

Stealthy spies are never suspicious, never seen, and never stopped. They are pros at fooling the enemy based on disguises, and cloaking past enemies is easy for them. They're not showboats (they're actually very cautious), but they can get the job done. They're probably the most useful kind of spy after the Mature Spy.

Characteristics:
1. Cautious
2. Great at acting
3. Uses odd routes
4. Useful

Advantages:
Enemies that aren't suspicious don't spycheck. Good disguises and cloaking abilities keep enemies from being suspicious. Who knows, they may even recieve an Ubercharge!

Disadvantages: They have very few, besides bad luck.

How to beat them: They tend to gravitate towards certain hiding spots to uncloak, so if you see one cloaking, spycheck those spots. They will not beat you.

Sub-classes:
Sap-Stabber (suggested by Haircut Police): Targets weaker classes, that are easily distrancted, like engy, medic or sniper. Very stealthy, plays cautiously and doesn't fight when it's risky. Preferred tactic: Sap a sentry, then when engie hits it to repair, backstab him. Usually uses a loadout based around cloaking.

Advantages: Very sneaky, knows when not to fight.

Disadvantages: Is easily outnumberd, slightly cowardly, lacks knowledge of how spychecking works.

How to beat them: Just spycheck well, pyros are useful for the fear factor appart from anything else.

Didn't expect that, did you?

Creative spies are hard to describe, because they're always doing something new. Any stats I try to offer on them will change as they do different things, so I'm not even going to try. All I can say is to be prepared for change, and adapt to a situation just as they do to win.

May I make a suggestion? Run.

These guys can do anything extremely well, after mastering trickstabs, gun/sapper use, and stealth. They are the true embodiment of spy. The only way to beat them is to spycheck and spycheck often. Bad luck is their one and only disadvantage. Dominating one of these guys is quite an achievement. Besides that, I really have no information on these guys whatsoever. It's really hard to analyze the patterns of someone who knows they're being watched.

Thanks for reading my guide! I hope you learned something, and I'm sorry I don't have enough info on Mature Spies. Also, if you have any additional troll spy sub-classes, feel free to post them in the comments! Thanks, and check back! I'll be making a guide with TF2 weapon ideas soon, and I'll post the link here!

ALERT! My next guide is in the works right now! It'e title: Creative Sentry Nest Destruction! It should be out in about a week. I'll post a link here.
Update: Next guide is done. Click the link below to view!
Creative Sentry Nest Destruction

I've compiled a list of traits/types. Use these traits to figure out what type you are!

Are you:

A showoff? Stairstabber/teenager

Useful? Teenager & up

Good with your gun? Weapons pro

Extremely experienced? Mature

Annoying? Stairstabber/Troll

Constantly changing your playstyle? Creative

Random? Baby/Shpee

None of these? Post in the comments what type you are. If I like your idea, I'll add it to the guide. Even if I don't other readers may learn something from it!