Noob Spy
Espionagus Noobus
Status: Very Common

We start off our list with the classic Noob species, of course. Noob Spies are akin to that of a baby horse. They are weak and clumsy at first, but will later develop into a more stable, and less helpless creature. The Noob Spy has not yet fully grasped the concept of cloaking, and usually ( accidentally) discover backstabbing as a result of this. They also are unaware of the spychecking method. They can be easily defeated without you doing anything. Just let them stumble in front of a nearby sentry and laugh at their unfortunate stupidity.

Status: Less Common than Baby Noob Spy
Yes, they are Noobs, but they differ from their "younger" counterparts so greatly that they deserve their own section. The Adolescent Noob Spy is still very noobish, but they are more skilled in the art of Spying. They can maneuver through a sentry nest and weaken it long enough for their teammates to nab the Intel or take control of the control point. They can sneak very decently and are good allies, but they have bloated egos and will do anything to be better than the other spies on their team. They are attracted to engineers and their builds like moths to street lamps. If you have discovered their pattern, they can be intercepted and eliminated.

Predator Spy
Espionagus Carnivorous
Status: Uncommon to Rare
As their name suggests, Predator Spies devote their entire existence to hunting others. They have no caring or sense of mercy. They are known to carry reskinned or alternate weapons and have excellent taste in hats and clothing. Unlike the Brash Spy that they so closely resemble, the Predator Spy hunts only for the sake of hunting. They also are known to be respectful of those who kill them, no matter how nooby they happen to be. However, they have a natural hatred for Pyros and a fondness for killing Snipers.
Ninja Spies
Espionagus Backstabbicus
Status: Somewhat Uncommon
Ninja Spies and Predator Spies are very similar in taste and weapon choice, but Ninja Spies focus entirely on the mission and kill only when necessary. They also differ in that they almost always dispise weakness and take pride in their leaderboard scores. They hate all other classes, especially Pyros, and will take every opportunity to torment nearby Snipers.

The Incognito
Espionagus Incognito
Status: N/A
It is unknown of the existence or rather, nonexistence of this mysterious creature. All that is known of him is that they blend into their team perfectly. They will stay in a role for nearly an entire mission to gain the trust of their enemy. They gain an important role and then use it to make the enemy team panic and fall apart. If your team is failing, and you have an Incognito Spy on your team, he may turn the tables on your foe to the point of an embarrassing, crippling defeat. These rare few are the most elite Spies and should be a welcomed team member in all situations. (Except for arena).

Brash Spies
Espionagus Narcissus
Status: Somewhat Common
The Brash Spy is essentially a rotten jerk hidden under the guise of a gentleman. Like any Brash species, they dress fancy and pretend to be fancy as well. But under all those layers of hats and clothes is a showboat who will do anything to look better than their colleagues. These people make poor teammates and you should generally avoid getting into feuds with them because they are very spiteful and quick to anger. You can mostly find them at the nearest staircase trying to repeatedly pull off stairstabs and facestabs, often with very poor results.
Troll Spies
Espionagus Hilarious
Status: Very Common
These guys aren't as bad as other players claim them to be. They just want to have a good time. Let's face it, the Spy class is the perfect class for trolling, so Troll Spies are by far the most common of them all. If you have one on your team, they can come in handy either as cannon fodder or just for the usual Spy business. Killing one is pretty much basically just as easy as your run of the mill spycheck. Don't forget to spycheck, kids.

SpyCrab
Espionagus Crustaceous
Status: Critically Endangered
Ah, the elusive SpyCrab, never shall you set your eyes on a more magnificent creature. Its a shame they're going extinct. This magnificent beast used to roam maps in swarms of hundreds, but now you may only see a lone SpyCrab scuttling by himself. These peaceful critters were hunted to near extinction because of wary engineers mistaking them for the believed to be extinct False SpyCrab. The False SpyCrab is the violent cousin of the common SpyCrab. They were a danger to structures and Hoovies alike. If you see a SpyCrab scuttling about all alone, think before you shoot. Guide him to any nearby safety so he may live in peace and happiness. Thank you for your time.

Credit to Fishiest Fish Hat Pyro for the discovery of this species
Paranoia Spy
Espionagus Hilarious Paranoia
Status: Somewhat Rare
This fascinating subspecies was unique enough to obtain it's own section. Like it's Troll Spy cousin, it loves to annoy it's prey before finishing it off. But unlike the Troll Spy, it is more cautious, and uses sounds and trickery to annoy it's prey. They often carry a Cloak and Dagger so they can stay hidden indefinitely. Upon entering the base of an enemy, it will yell "Spy!" to induce paranoia among the local Engies. As soon as they move their Sentries to more strategic places, the Paranoia Spy gets to work. It saps any and every building, and allows Engies to build more before starting the process again. After a while, it will become bored, and will take the Intel and leave.

Many thanks to everyone for this suggestion
Dead Ringer Spies
Espionagus Opossumus
Status: Somewhat Uncommon
While I was never a fan of the Dead Ringer, preferring the efficient Cloak and Dagger over anything else, this seems to be a popular item among the more daring of Spies. Oh, how many times a have killed an enemy Spy, only to have my spinal column violently penetrated by that same Spy only seconds later! Although tricky to use, the Dead Ringer can become a lethal tool for those who know it well. Thus beginning the life of a DR Spy. Elusive and cunning, the DR Spy uses all of it's enemies against themselves. Upon being shot, they will drop a decoy, tricking the opponent into believing they are dead, when suddenly, the intel is taken, your builds have been sapped, and you can hear the gratings sound of French laughter in the distance. They can be good allies, but make enemies furious, often to the point of rage quitting.

Jailbreak Dead Ringer Spy
Espionagus Opossomus Duplicivitus
Status: Very Common
This is a more common subspecies of the Dead Ringer Spy, named after its use of the Dead Ringer as a "get out of jail" card. Despite their unorthodox method being very poor for survival, the Jailbreaker defies the entire concept of natural selection, and is a more successful species of Dead Ringer Spy. It is also one of the most hated species of Spy in the entire game, even by other Dead Ringers, who look upon their brothers in shame that their beloved tool of mayhem is reduced to a crutch for poor players.

Hermit Spycrab
Espionagus Otaconus
Status: Somewhat Uncommon
This relative of the Spycrab is a recent mutation that occurred after the Gun Mettle update, which brought a specific trait of the Hermit Spycrab: The Boxtrot. Hermit SpyCrabs live peacefully inside their boxy shells, huddling in corners for safety. This behavior has earned them nicknames such as the Boxcrab and the Boxtrotter. They aren't very noticeable because they sit motionless when they feel threatened, trying to blend in. If this fails, they will abandon their shell in order hide themselves and flee. Their population has seen a slow incline since they were introduced, but they thrive on large servers such as dm_mariokart.

False Noob Spy
Espionagus falsarius
Status:Rare

Credit to theothanos for aiding in the inclusion of this species
The False Noob Spy, alternatively known as the False Gibus Spy, is a lovely example of aggressive mimicry. Instead of mimicking a predator to appear as deadly and ferocious, the False Gibus Spy mimicks its cousin the Noob Spy to appear less threatening to a threat. For years, scientists have wondered how and why an organism would adapt to appear weaker, but recent studies have revealed a fascinating behavioural trait uncommon to many species of Spy.

The False Noob Spy uses its weak appearance as a lure. Instead of ambushing its prey like almost every other species of Spy, the False Gibus uses achievement-unlockable cosmetics (most notably the Ghastly Gibus), to lull its opponents into a false sense of security. They feign ostentaciousness to gain the attention of a foe, most commonly and Engineer or Medic, and lure them into an area where they can perform a deadly trickstab maneuver on its hapless prey.

While the False Gibus may be a terrifying predator for some classes, they are actually in the middle of the food chain, being preyed upon by Heavies, Soldiers, and especially Pyros. If you have trouble separating an enemy Engineer from their Sentry, a False Gibus may prove a useful asset to your team, but if an enemy Pyro patrols its base regularly, you may need to find a more stealthy approach.

Sniper Mimic Spy[/b]
Espionagus Australius
Status:Rare

credit to theothanos for the discovery of this species
This rare species of spy has an immense love for the Ambassador, which I might even call an emotional dependence. While ordinarily Spies with the Ambassador will use its headshot if they need to kill a pursuer quickly, the Sniper Mimic does not. Instead it has evolved a behaviour similar to that of a Sniper itself, keeping at a distance and painting the walls with grey matter from far away. Because the Ambassador lacks a zoom function, the Espionagus Australius often goes without a successful kill for a long period of time, maybe ending a match with one or two lucky kills on some Hoovies or an absent-minded Scout. You might be better off leaving this species alone once you encounter it, as this species is known to hold a bad grudge.