Simply put, a Mook that flies, floats, or hovers, due to either having wings, a propulsion system, or supernatural powers. They may stay out of the player's reach, and will attack him from their advantageous position. Furthermore, due to their freedom in the air, they may tend to dodge rather well.
Because of this, they can be considered Goddamned Bats or, in worse cases, Demonic Spiders, especially in games where your character has Denial of Diagonal Attack or takes Knockback (see Ledge Bats for this case). Can be a type of Kung-Fu Proof Mook if they're especially hard to hit normally.
These guys usually tend to do one of the following:
Stay out of the player's reach and shoot them or drop bombs (or Mooks) from above.
Airborne Mooks in Platform Games, usually those that try to knock the player over, are considered a huge annoyance, especially if they're the kind whose sole purpose is to knock the player into a Bottomless Pit.
Airborne Mooks in FPS games or Action games may be smart enough to strafe around the player, making them harder to hit. Other than that, they use the same strategies above.
RPG games will tend to have these guys as Fragile Speedsters. They'll usually have a high speed and evade rate, making them a pain in the ass to hit. Thankfully, they probably won't have high Hit Points, and will go down quickly if you do hit them. In the case where they do have high Hit Pointsand a high evade rate (and maybe some very damaging attacks), you're fighting a Demonic Spider.
If these things appear in a Tower Defence game (especially those where you have to divert the mooks' path), they'll usually have the ability to take a short cut and fly over your towers to their goal. Certain types of towers will not work on them either.
Your best bet against an Airborne Mook is, obviously, to use an Anti-Air attack against them, as they'll usually be weak to it or are unable to avoid it. If such attacks are not available, then a ranged attack will do.
Alan Wake had the Taken Crows, which were obviously extremely weak, but attacked in whole swarms to compensate. Alan Wake: American Nightmare had replaced them with Taken that could temporarily turn themselves into swarm of crows.
American McGee's Alice had only the insectoid Bolterlfies as its flying mooks. Its sequel Alice: Madness Returns had much greater variety. Besides Bolterfly-like enemies, there were also the Drifting Ruins, which fired shots that crystallised into spikes when they hit the ground and the Bitch Babies, which literally vomited acid down you and could have it reflected right back at them.
Madness Returns also had the Samurai Wasps: an entire class of Airborne Mooks, with regular katana Wasps, the ranged archer Wasps and the elite Naginata-wielding Daimyo Wasps. There was also originally supposed to be a Wasp Queen as a level’s boss, but time constraints had forced it to be removed alongside the bosses of all other levels besides the the last one.
Alien Hominid has helicopters and jetpack guys, both of which can take a lot of damage.
Alien Soldier has the irritating flies, which are weak, but hard to hit (except with the homing force).
Area 51 2004 had the translucent, spherical aliens that floated in the air.
BioShock and BioShock 2 had the security drones, which flew around thanks to having helicopter rotors, had either machine guns or rocket launchers were activated if you stayed too long in front of the security cameras on some levels. However, they became your allies if you managed to hack the security cameras, and BioShock 2 allowed Delta to have the drone itself with a Hacking Dart.
The Mosquitoes in Bioshock Infinite wil attack you on sight and have a chaingun instead of regular machine gun, but are otherwise the same. Friendly ones could also be summoned by Elizabeth from other dimensions throught the use of Tears.
System Shock also had certain unlucky members of the crew, which were mutated by SHODAN into some sort of a completely transparent flying ray. Besides being agile and difficult to spot, these also spat acid.
One of the enemy types in [[Cryostasis Cryostasis Sleep Of Reason has grown large, moth-like wings and strafes around a lot, making them hard to hit.
Devil May Cry generally has one or more of those per game. Of note are the Bianco Angelos and Alto Angelos (White Angels and High Angels in Broken Italian) in Devil May Cry 4, which combined this trope with Shield-Bearing Mook: their wings could also fold together as a shield.
Earlier, Devil May Cry 3 had the feminine Fallen Angels, which shielded themselves from attacks with their white wings. They had to have them shattered while in flight to bring them down to the ground, then defeated before having time to regenerate these.
Eternal Daughter had many of those, including extremely fast bats and the circle-flying jungle parrots. The jungle also had continuously falling leaves, which had pygmies on them. Cute as it was, a collision with them inflicted a sizeable amount of damage.
Garden Gnome Carnage has sleighs. They float, and some of them drop gift-clad parachuting elves on you, but on the other hand, they can be helpful as they explode like a brick when they hit the ground, likely taking out some elves in the process.
In the Garden Gnome Carnage spin-off Hyper Princess Pitch, they return. They shoot projectiles at you, and some of them only fly by, leaving you only short time to kill them, while others stay around and you have to destroy them.
Goblet Grotto had the “mosquitoes” (which looked like football-sized cross between mosquito and a fly) and the 1.5 meter tall albatrosses, which attacked with the two daggers they held in their paws.
Grid Warrior has several, usually of the Wind element. Most attacks cannot target them while they're airborne, except for lightning and ice weapons, Holy Bullets and the Flak Cannon (which does extra damage to them). Most of them have to fly low to attack the player, allowing a player without those weapons to harm them.
Gunstar Heroes has jetpack soldiers that drop bombs in Orange's stage.
Half-Life 2 had the Manhacks – small drones deployed by Overwatch, whose only function was close the distance and cut you up while they’re shooting at you. There are also the Combine Choppers and Gunships, though these are either bosses or justified Boss in Mook Clothing.
Plenty of those in the earlier Harry Potter games. There are pixies, which strafe around and throw magical projectiles, Billywigs (effectively just very large flying mosquitoes), small Books That Bite that ambush you from certain bookshelves (as opposed to large ones that shoot spells and act like mini-bosses) and more.
The third PS2 game had flying torches and self-moving fireballs, only around in the Hermione levels, as she was the only one who had the freezing spell needed to deal with them.
Jaws Revenge had the helicopters, which dropped the Explosive Barrels onto your shark. However, it only took three hits at most to bring them down.
Dark Forces had the Imperial probes much like in the films, which flew around and attacked with electric shocks. There also were the Dark Troopers, which spent most of their time in the air due to having jet packs, were tough to kill and were always equipped with heavy weapons.
Killer Is Dead had the Wire drones, which would fly around and pepper you with gunfire while you’re busy fighting regular Wires on the ground. They’re more of a nuisance due to protagonist being Made of Iron, however, and are quickly shot down with his Arm Cannon.
Mercenary Kings had several airborne robot enemies. Some are rather weak and more of an annoyance, (Flyer, Ghost) but the Bomber and the Copter Turret are both very powerful.
Metal Slug has the dangerously annoying helicopters and missile aircrafts.
Mystic Towers had one of these in each tower. There’s a flying fungus named Fungafly, a so-called Bagfly, bird called Monobeak, jellyfish-like Stinger, Snapdragons and Verdragons, etc. There were usually slightly weaker than the land-bound enemies, but also faster and couldn't be avoided by levitating away from them.
NieR had robotic drones which attacked you with lightning and some sort of magic bullets.
Prototype and its sequel had their protagonists so powerful that the helicopters, normally reserved for Boss Battle|s in games or at least acting as Boss in Mook Clothing, became this trope. After all, both Alex Mercer and James Heller could just jump up to their level and kick them out of the air.
The AV-48S Seraphim security robots in Remember Me. These fly safely beyond the reach of your melee attacks and fire energy projectiles. They’re also protected with shields most of the time, forcing you to time the long-range Spammer shots to when they lower it to get it recharged. Luckily, they’re also Glass Cannon|s and are destroyed with just two Junk Shots.
The Harpies from Serious Sam, and the Flying Kleers, Floaters, Hellchicks, and Levitators from Serious Sam 2. They all possess projectile attacks, whether they be fireballs (Flying Kleers), energy projectiles (Harpies, Floaters, Levitators) or bats (Hellchicks).
The Dragonlings in Shrek the Third tie-in game. Subverted in that most of them still fly low enough to be within reach of Shrek’s fists or Arthur’s sword. An elite white dragonling doesn’t make that mistake, however, and will only come down right before attacking.
The so-called Electricians in You Are Empty. Basically, they were the zombies with helicopter-like blades on their back that would fly dive down and attack you with their arc welder.
Action RP Gs
Borderlands had the Rakk, which were hard to hit in the air due to their attack patterns, but could be comfortably killed with shotguns once they dived down to attack you. Borderlands 2 also added the Hyperion Surveoyr drones, whose main purpose was to repair the Loaders on the ground and occasionally hit back at you with weak electrical attacks.
Borderlands 2 also had the JET Loader, which was effectively the basic GUN Loader capable of temporarily transforming into a jet and attacking from the air. They weren’t much of a challenge … but same couldn’t be said about the miniature version that came out of some ammo chests. Its reduced health was more than offset by always having shielding and being much harder to hit.
The alien drones in The Bureau: XCOM Declassified. They will frequently strafe around and either heal their allies on the ground or levitate you or the squadmates off the ground with the short-range beam, allowing other aliens to pump you full of plasma.
The Giant Mosquitoes in the Blighttown swamp in Dark Souls. Hard to hit, annoying things. They're easily killed by the even the weakest of attacks but here is the kicker; They endlessly respawn.
Kingdom Hearts had plenty of those. One of its traditions has been that mage enemies (whether Heartless or Unversed) are hovering sphere-like enemies that cast from their chosen element and have two part names. First part is their colour, second is either type of song (Heartless) or a spice (Unversed).
Vespoids in the Monster Hunter series. They are essentially giant wasps that hover just out of reach of many of the game's weapons, before darting in, jabbing you with a stinger, and retreating. Couple this with the fact that the stinger can inflict paralysis on you, and will seemingly always do this when you're low on health/fighting a boss level enemy, and you will soon come to hate them.
Also, they nearly always shatter when you DO kill them, leaving absolutely nothing to loot, making the whole exercise of killing them completely pointless (fortunately, Poison works fine if you need a body to carve).
The fact that the developers have included quests based entirely on slaying large numbers of these things (an early quest has you slay 20. At this point in the game, it takes 3-5 hits to kill one of the things!) also accentuates the utter irritation they bring. However, at least they spawn almost infinitely in certain places, so you don't have to go looking everywhere for them.
Halo had Drones as flying enemies from the Covenant. And Forerunner Sentinels.
Bug! also had at least one in each level, and they were usually very annoying to defeat.
Castlevania I gives us the gorgon heads. They don't usually turn you to stone, but they do fly in a sine wave when you're on platforms. If the platforms are moving, they becomes Demonic Spiders rather quickly.
A lot of the flying demon enemies in the future 2D entries also do this. The sheer amount of mid-air enemies makes the Axe subweapon very good in these.
Commander Keen 4 has Skypests. Can't shoot them, can only crush them with your pogo stick when they land.
Iji had the Skysmasher drones in its last level. Not only did their flying pattern make them hard to hit normally, but they also did something no other enemy could – their Shocksplinter projectile was fired alongside the ground. Thus, the ducking move, normally foolproof against explosive projectiles, was 100% useless.
The Mega Man (Classic) series had many Mecha-Mooks that could fly. Some of the more irritating ones were "Pipi", a robotic bird carrying an egg which it drops. If the egg hits the ground, it would break into 8 or so mini-birds, which would then fly at Mega Man. Especially annoying were those "things" that lived in Bottomless Pits which popped out from them as you jumped over, knocking you backwards and into the pit.
Metroid Prime features flying space pirates. And, of course, wasps!
Ninja Senki features one in every level group. The ghosts in sections 1 & 2, Purple Flames (these fly high and drop small flames onto the ground) at sections 3 & 4, demon heads going in circles around you on sections 5 & 6, etc., etc.
The Super Mario Bros.. games have: Lakitu, who flies out of normal range and drops spinies onto the player; Koopa Paratroopas, flying versions of the regular Mooks; and Bullet Bills, which try to ram the player, as some of the notable ones.
Infinite Adaptive Mario, a Java remake with self-adjusting difficulty, contains Para-Bullet Bills
Terraria has a number of them, including demonic eyes and eaters of souls.
Wide variety of them is abound in The Binding of Isaac. Many are varieties of a fly, starting from regular red flies that have tiny health and only do contact damage, all the way to fast, tough Boom Flies that explode on death. In between there are the ranged Pooters and the smaller ladybug-like things that also explode on death, but are much slower and weaker than Boom Flies.
There are Hofers – eyeless heads suspended in the air that spit blood and a variety that moves while doing so. Then there are relatively high-level Babies, which shoot blood and constantly teleport, and Angelic Babies which fire a Spread Shot of three. The Womb has Leeches, which charge forward through the air at ridiculously high speeds if you’re in their path, with the upgraded Explosive Leeches and Angelic Leeches (also Explosive, but are protected by an invincible fly) encountered at Satan’s level and Cathedral, respectively
The legendary bats of Spelunky, which have a great detection range, but poor pathfinding and are thankfully one-hitpoint wonders. The Jungle levels occasionally have Vampires that can turn into Bat-form to keep things fresh. Then, the Ice Cave levels have laser-firing UFOs whose shots can irrepairably destroy the platforms.
The paid Spelunky remake also has the Jungle Wasps, which are tougher and more dangerous than bats.
Fallout3 had the Bloatflies, which attacked by spitting their larvae at truly unearthly speeds.
Fallout: New Vegas added the similar, but much tougher Cazadors as well as Mr. Handy robots and their tougher Mr. Gutsy version.
Final Fantasy XII had some enemies with the flying status, which meant that you couldn't use melee attacks against them unless they were guns or bows/crossbows. Alternatively, one could just use magic on them without having to open up the inventory all the time.
Final Fantasy VII also had enemies with the "flying" status which could not be damaged by melee attacks. There were also bat enemies which had a 1/8 (later ones had 1/4) chance of completely avoiding a physical attack, making them literal Goddamned Bats.
The Mario & Luigi series has them. Hammers and other low-hitting moves will not be able to hit these kinds of enemies, use your Goomba Stomp instead. Bowser from Bowser's Inside Story has it pretty rough against the (very few) airborne enemies he fights - he is unable to attack them via any of his normal attacks.
Mario & Luigi: Dream Team adds mooks (and bosses) that change from being airborne mooks to land based ones mid battle (and vice versa), with Flibbees going between being right way up and on the floor and upside down and in mid air. There's also Robo Drilldigger, a giant boss who has both land and sky forms (and whom is immune to the jump or hammer depending on which one is in use) and the boss Pi'illodium, who can thankfully be taken out the air and made vulnerable to ground based attacks if you destroy its wings.
Flying Assault Drones and Rocket Drones in Mass Effect 1. Their flying made them immune to most biotic attacks, they had some of the strongest shielding in the game and very tough weapons to boot. They land eventually, though, and could be lured to your side with a high enough Hacking skill. Ironically, the much weaker Geth Recon Drones are the first and weakest enemies you face in the game.
Mass Effect 2 nerfs the Rocket and Assault Drones, but allows enemy Engineers to create small drones of their own. These have very low health, but are fast and usually attempt to flank you and dislodge you from cover using their melee electric shock attack. Luckily, engineers can create their own.
Last but not least, Mass Effect 3 has the Harvesters. Made from a wild, non-sentient specie, these are very tough, have a powerful cannon attack and spawn more basic husks around them. The multiplayer also has the very fast Geth Bomber drones with difficult-to-dodge attacks.
Goddamned Zubats from Pokémon, or any Flying-type for that matter, although they weren't as annoying as the bats...
Pokémon with the Levitate ability to dodge Ground-type attacks can count too, though Koffing/Weezing are probably the most annoying, having a high Defense, being able to poison you or blow up, and having only one weakness because Levitate removes its Ground weakness...
The Tynamo family is particularly nasty for this reason; its offensive stats are high enough that it can do more than stall, and its weakness to Ground attacks is annulled by its Levitate ability, effectively leaving it with none. That is, unless Gastro Acid, Entrainment, Gravity, Mummy, or Mold Breaker come out to play.
Heavy Weapon has your tank on the ground, and most of your enemies in the air. There are some ground-based enemies too, which can sometimes be more annoying than the aerial ones.
Dead Space had the sorta-flying Infectors, which were weak but fast, and whose main purpose consisted of making more Necromorphs from the corpses lying around. Then, the Dead Space 2Severed DLC has had the actual winged Flyer Necromorphs. Thankfully, those were also the weakest of the bunch.
Dead Space 3 has a Necromorph formed from the alien spore plant that is only encountered in Zero-G environment and will shoot you with its spores.
Obs Cure and its sequel had the university girls mutated into moth-like flying enemies, which also had a habit of attacking in swarms.
The infamous Air Screamers and their Otherworld version, Night Flutters, in Silent Hill 1. They only appear when it’s dark and foggy and usually aren’t spotted until your siren starts ringing. Avoiding them is difficult because they fly faster than you and are smart enough not to fly straight to your location but will circle you and then attack. Fighting them is even worse, as they attack out of reach of melee weapons unless it’s too cramped for that (and even then, they can’t be attacked by knife at all), forcing you to waste seven Handgun bullets to bring them down.
Silent Hill 3 had the Pendulum, a whirring machine-like thing that flew like a helicopter with blades of rusted metal (which it eagerly used to cut you up as well, of course.) Silent Hill: Homecoming had the airborne insectoid swarms, which would cling to Alex and drain his health over time.
Also, Silent Hill 4 had relatively weak Mothbats, which were notable for weakness to Bug Spray and being capable of distracting the ghost of main antagonist from pursuing you.
Two kinds of flying enemies appear in Defense Grid The Awakening, one of which just has more health than the other. In any case, both of them are very dangerous as they are immune to some towers, and cores stolen by them cannot be replaced.
Age of Wonders had various flying units for each faction. Usually, they were amongst its most powerful, like the dragons, White And Dark Angels, the cat-wyvern-like thing, the air elemental and more. It helped that they were practically invulnerable to the melee attacks (unless those were the counter-attacks in response to be hit) and practically had to be wailed down with ranged units (that had a habit of missing) or the expensive magic.
Fire Emblem throws Pegasus Riders, Wyvern Riders, and, occasionally, flying monsters at the players on a regular basis.
Heroes Of Might And Magic 3 generally had one or two flying units per race. Some, like Citadel Lightning Birds or the Tower Gargoyles, would only cover 7 squares or so, while others, like Angels, Pegassi or all dragon types, could fly to any square on the board. The Dungeon faction Harpies deserve a special mention: when upgraded, these had the “Return Back (to a starting point) After Striking” and “Enemy Doesn’t Respond To Blows” trait, which essentially made them into a ranged unit that could attack with impunity and flee if a stronger unit cornered them.
Heroes Of Might And Magic 5 had a smaller selection of races, but tried to give them more variety to compensate. As such, the flying units also gained more unique traits. For instance, Gryphons could fly off the map for one turn to dive down at your chosen spot in the next. If the enemy troops were still there, they would receive doubled damage from the attack.
Nippon Ichi strategy-RPG titles feature a variety of flying creatures, including angels, succubi, and assorted monsters.
Super Robot Wars includes a broad selection of flying units, both giant robots and more conventional aircrafts.
X-COM has Floaters in the first game and an assortment of similar aliens in the sequels.
In Airborne Avenger, the villain's Mooks get around with hang gliders... while the hero uses a one-man flying jet-sled.
Transformers Prime, some of the Decepticon Vehicons have jet forms. Then there's the Insecticons.