I'm sorry, no, I won't take it. If we accept orc zombies, then we open the gate to all kinds of crap. What's next? Centaur dragons? How about demon fairies? Maybe buffalo elves? Heck, why not whale vultures? I'm going to make a stand for plausible monsters everywhere. Who's with me?
Transformation: An already non-human creature gets an incomplete Baleful Polymorph, is infected with The Virus, bitten by a werewolf, or grafted with cybernetics or subjected to genetic engineering. What happens here is you have a "common" base type which gets superseded by a second one. Common subtypes include: Vampire-elves (again), <<species>>-skeleton, <<species>>-zombie, cyborg-demon (more common than you'd think), and mutants of any such species in general.
The Darkness of the Book of Darkness at the end of Magical Girl Lyrical Nanoha A's, likely a result of the Wolkenritter collecting Mana from alien magic beasts as well. Its body included the black wings and upper torso of Reinforce, the rocky protrusions and and metal plates of the giant turtle-like beasts, and the tentacles of the Sand Worms, along with other parts like giant red horns and spider-like legs it got from who-knows-where.
Ranma ˝ has Pantyhose Taro's cursed form, which in his first appearance is a Yeti/Bull/Crane/Eel hybrid. By his second appearance he has also added Octopus.
In Pokémon Special, there is a stone statue in Eterna City that features a cross between Dialga and Palkia. This is later explained as people once thought the two beings as one.
And of course, there's Zapmolcuno in the first arc of the manga, a chimera created by Team Rocket by fusing the bodies of the three Legendary Pokémon, Zapdos, Moltres, and Articuno.
An early episode of the anime has Venustoise, an illusory fusion of Venusaur and Blastoise.
The Hybrid Bakugan of Bakugan Battle Brawlers were created from the collision of two elemental planes. As a result, all six of them are sort of cruel mockeries of their combined elements with personalities to match.
Digimon Adventure 02 took quite a shine to this trope - it pretty much started with Chimeramon (and by extension, its evolved form Millenniummon from the WonderSwan games), then proceeded to combine this with Fusion Dance for Paildramon and Silphymon.
The Nyokai from The Twelve Kingdoms. The more varied animal parts they have, the better. Special mention goes to Taiki's own, Haku Sanshi: she has the head and torso of a white-haired girl, the eyes of a fish, the tail of a lizard, and the lower body of a leopard.
Even her personality is Hybrid. The transfer to Wa (Neo-Japan) changes her mode of thinking from gentle mama-tiger to homicidal guardian who knows how to cause car accidents. And somehow, the demon lord that guards Taiki (don't ask) doesn't seem to care...
Marvel Zombies had just about every Marvel Comics hero and villain turn into a zombie. Which was a space virus. We'll let you ponder the ramifications of Zombie Wolverine, Zombie Human Torch, and Zombie Hulk for yourself.
One of its titles crossed over with Army of Darkness Ash, it ends the comic with him escaping to a world where all the heroes are infected with lycanthropy.
The third book had Morbius, a Zombie Vampire (or a "Vambie" as he states).
Disregarding the whole "space alien" backstory thing, Two-Edge from Elfquest would technically qualify, being half-elf, half-troll.
The titular Monster Plus is a one-man Monster Mash - he's a vampire werewolf Frankenstein's monster zombie mummy witch doctor. Originally, he was just a Frankenstein's Monster, but when you get into the kind of scrapes he does you pick up some unique skillsets and/or bite marks.
You could arguably include his enemies Hitlerfist and Supermane; Hitlerfist is the monster with Hitlers for hands, while Supermane is, well, Superman with a lion head.
This is the driving force behind the plot of Underworld, Lucian wants to create a hybrid of the (biological) vampires and werewolves so he can finally win the war between both species in his (the werewolves) favor.
The sequel gets interesting in this regard. While Michael is a Werewolf-Vampire hybrid, Marcus becomes a Vampire-Werewolf hybrid (which means he gets wings, but is still nocturnal). Selene herself gets "hybridized" with Alexander's blood, making her not so much a Vampire-??? as pure Bad Ass, as well as immune to sunlight.
The fourth film features Selene and Michael's daughter who was conceived after they had both become hybrids themselves, so she was born as a hybrid of two hybrid species. The Dragon to that film's Big Bad was also a hybrid of sorts, being a werewolf whose DNA had been spliced with something that made his wolf form twice the size of a normal werewolf and made him immune to most of the traditional werewolf weaknesses.
Technically, the warrior aliens we are so used to seeing in the Alien series would be a alien-human hybrid (The Newborn from Alien: Resurrection also would count), and the creature from Alienł would be an alien-dog hybrid.
By that logic, The Proto-Xenomorph "the Deacon" in Prometheus would count as well, being an alien born from an Engineer.
The Fly has Brundlefly, a six foot, 185 pound, acid spwewing man/fly hybrid.
Splice has Dren, a female creature that is part human, and any number of other animals, depending on how many 'plug and play' samples were inserted into her DNA at the time of her conception.
The talking-donkey/dragon hybrids from Shrek 2 qualify, though as they're all fluffy little foals they're hard to see as monsters.
The Xanth series abounds with this, due to the magical love springs which created the world's Half Human Hybrids in the first place.
Although the White Witch from the Chronicles of Narnia claimed to have at least partial human ancestry, she was actually a hybrid of giant and jinn (genie).
In Christopher Stasheff's A Wizard in Rhyme series, there's a dracogriff. He's half griffin, half dragon. Unfortunately, this is not quite as awesome as it sounds, since griffins and dragons are bitter enemies and he's hated by both.
Harry Potter: The Ministry of Magic has explicitly outlawed experimental cross-breeding. Not that this prevented Hagrid from breeding Manticores with Fire Crabs to produce Blast-Ended Skrewts.
The cockatrice on Merlin was originally going to be one of these - ◊. But somewhere along the way it just became some kind of dinosaur thing. The makers apparently saw sense and cast the creature pictured as the Questing Beast, of which it is a fairly mythologically-accurate portrayal.
Besides the aforementioned Tuvix, Star Trek: The Next Generation featured at least one half-klingon half-romulan. Also, of most species featured in the Borg's species registry, there exists (or existed) a cyborg-zombie variant.
Except for the Kazon, the only species ever deemed unworthy of assimilation. In a universe with thousands of species, that's a major burn.
In Grimm, one episode features a hybrid-Wesen, created after a Genio Innocuo mother felt they were too passive-aggressive and spliced her son's genes with that of a Lowen. Unfortunately, this created a Jekyll & Hyde situation as since the Genio Innocuo are naturally competetive, the Lowen side would manifest to murder their competition.
Paragon prominently features a lion/eagle/lizard hybrid griffon on both its backglass and playfield.
The Gorgimera, with three heads: manticore, black dragon, and gorgon.
Not the Medusa gorgon, but a bull-like demon with petrifying breath.
The players can become this with some effort, for example, one can become a half-CelestialMinotaurWerebearVampireLich via templates added to your character. Note that this particular one is impossible, as an half-Celestial cannot become a vampire, and a vampire cannot become a lich.
The monster sourcebooks contain lots of hybrid monsters, like the Drider, which is like a centaur but with a Dark Elf top half and giant spider bottom half.
d20 uses "templates" which graft part of one monster type onto any existing one. This can be used to make half-dragon wolves or half-angel kobolds. Templates can even be stacked, to make stuff like half-fiendish half-troll half-elemental pseudonatural vampiric werecrocodile goblins.
There was an essay exploring the possibility of a vampire werewolf,with one of the major points of contention being whether the undead nature of the vampiric template would override the lycanthrope's shapeshifting ability. Of course this requires the templates to be applied in the proper order, as lycanthropy is a disease and undead are immune to all disease, so a vampire cannot contract lycanthropy.
3.5 sourcebookBastards and Bloodlines (from Green Ronin) contains over 30 different half-breeds, from the believable (Mergs [human/merfolk]) to the silly (elf/giant eagle, halfling/blink dog). They also provide the option of creating your own, if you find the options unappealing.
Perhaps the least dangerous of all is the duckbunny. It's created by apprentice mages who want to practice making ridiculous hybrids without risk of being eaten by the result. (Obviously, Wizards of the Coast was having a little fun with the idea when they came up with this one.)
DeadLands: Hell On Earth has vampire werewolves in the main handbook.
Malfegor isn't the best, but he sure as hell qualifies, what with being a half-demon, half-dragon... thing.
Warhammer has, among other things, Dragon Ogres) which, confusingly enough, are not related to normal Ogres at all), Skeleton Giants (which may or may not include any Giant bones — really they're just oversized bone golems), Zombie Dragons (Exactly What It Says on the Tin), Chaos Dwarf Bull Centaurs and Chaos-corrupted versions of just about anything. Chaos at least includes a kind of Hybrid Overkill Avoidance in that anything with too many mutations devolves into a shapeless Chaos Spawn.
40k has the Soul Grinder, essentially a Cyborg Daemon.
This happened rarely in the Old World of Darkness — more common in the early editions, but then the writers decided that such a thing was too gimpy. There were some exceptions, such as the Abominations (werecreatures who'd been Embraced, forced to live out a hollow and torturous existence as the natural world rejected them utterly) and the infamous case of Samuel Haight, the Kinfolk turned werewolf with vampiric Disciplines and Awakened magic (who eventually got killed and turned into an ashtray).
Largely impossible in the New World of Darkness, where being one type of supernatural creature cuts off the chance of being another type. Werewolves are immune to the static effects of vampire blood because they're shapeshifters (though they can still be addicted to it...), mages are killed if you try to Embrace them, Prometheans don't retain any supernatural qualities of the body used to make them, and so forth.
Last Res0rt makes this the default form of the Celeste; literally, they're made up of all sorts of different species, to the point that there's no such thing as a "purebred" Celeste, and they seem capable of mating with any (sentient) species.
George the Dragon has the offspring between the titular George and the Loch Ness monster. Plus a lobster, for no explainable reason.
William: The current known record for number of parents to a single child is twelve, and only nine of those were Uryuoms.
The Order of the Stick has Malack, the lizard person-vampire, and now Durkon, the dwarf-vampire. Also, Girard (or Girard's Gate fame) apparently had some dragon ancestry.
Common in Fairy Dust. Any humanoid can breed with almost any other. Some particular cases happen:
Incubae's traits are exclusively found on the Y chromosome. An incubus's daughter is not an incubus (or a succubus). The race can only reproduce with a female from another race. The typical incubus is such a genetic patchwork that it's hard to tell what his family tree looked like.
Tiny elves hybrids are great elves, the genetic defect making them tiny, sickly, and obligatory cannibals being corrected by outsider blood.
Monster Rancher, a popular take on the monster-raising genre, has this as the main monster differentiation. In any one game there'll be 20-25 base breeds. Main/Sub is the most common shorthand i.e. Golem/Golem for a Main Golem/Sub-breed Golem "purebreed." If you mix it with a Hare/Hare you might get a Hare/Golem or Golem/Hare.
The Zerg and Protoss Hybrids are part of a major story arc in StarCraft. It started in the secret mission of Brood War with Zeratul finding them in cryo-suspension on a remote dark moon, and by StarCraft II it has been confirmed that not only are they spread throughout the Galaxy, but they are waking up and will bring forth the end of the Universe under the command of the Fallen One.
Druids can shapeshift into a Moonkin, a combination of the wisest (owl) and strongest (bear) animals.
Doom has Mancubi, which is a demon with guns for hands and robot legs; Arachnotrons, which are giant brains with robotic spider bodies; and Cyberdemons, which have a rocket launcher for an arm, one robotic leg each, and wires for a midriff.
Those aren't really hybrids, they're more like a demonic Hollywood Cyborg. Doom 3 did include a few, though. The Cherubs (half-infant-half-insect, and the Vagary (half-lady-half-spider).
Whilst the Castlevania series uses a lot of mythological monsters, it also creates its own, like a monster which is half zombie skull half butterfly. And half naked chick and half dinosaur.
Nero Chaos in Tsukihime. Technically, he started out as a human but now shares his identity with 665 other creatures, so the actual humanity he has left is essentially negligible. Capable of some degree of shape shifting between forms and also something of an ultimate killing form that isn't described very well. His body includes dogs, tigers, at least one doorshark, bears, dragons, unicorns, a blue crow, one vampire, some jaguars, giant crab monsters, stags, wolves and who knows what else.
Add a deer to the bunch. Or that was for his cat counter-part, Neco-Arc Chaos.
Touhou has Keine, a were-hakutaku. Umm... a hakutaku is something like a giant lion with extra eyes and horns. In practice, this really means that on nights of the full moon, Keine grows horns, a tail, changes in power and hair color, and gains new superpowers. Because people don't really know what a hakutaku, much less a were-hakutaku, is, fan jokes tend towards portraying her as a cow.
Goosebumps: Escape from Horrorland has terrifying crab-slug hybrids lurking within the labyrinths found inside the park's trash cans. It's never explained what exactly they are or how they came to be; even the name of their species is only found in the manual.
Final Fantasy XIII gives us, at the very least, cyborg wolves and Behemoths (with Tron lines, no less!); however, as well as "recognisable" hybrids, the game also treats us to a whole menagerie of weird and wonderful mash-up monsters that defy description. In particular, this Troper isn't entirely sure what certain Annihilators like the Proudclad are supposed to be, but it can't be pleasant.
In Shin Megami Tensei: Strange Journey, the crew of the Red Sprite find a demon in Mitra's palace being tortured by the other demons. An examination reveals it's made with equal parts demon and human DNA. Jiminez, showing a softer side for the first time in the game, saves its life by adding it to his Demonica and names it "Bugaboo" (the only word it can say).
RuneScape has Newtroosts, Unicows, Spidines, Swordchicks, Jubsters and Frogeels. You make them yourself, player.
Nightstalkers in Fallout: New Vegas are a cross between a coyote and a rattlesnake. They look about as strange as you'd expect.
AdventureQuest has Fur Against Fang as a major theme in the Darkovia region. There are also a few Werepyres running around. And then someone had the bright idea to take a Werepyre and add some Dragon to the mix, creating Nightbane the Dracopyre. His bite also infuses ordinary Vampires and Werewolves with some draconic traits.
The Chimera of the Tomb from Dark Souls is a white lion with ram horns, four bird wings and a scorpion tail.
Many of the husks in Mass Effect are this as the Reapers like to experiment. Scions are basically three organics mashed together with a big gun, Cannibals are batarians crossed with humans and the Brutes are a krogan crossed with a turian. The last is probably the worst as those two species aren't even genetically compatible.
In Borderlands 2, one quest chain for Dr. Zed has you collect body parts from rakk, skags, and spiderants. The former two are made into flying skags called "skrakks" and the latter is combined with parts from a psycho to make a "spycho". Hilariously, when you go on the third quest, Zed tells you that it's technically your fault since you agreed to get the parts for him.
The entire mechanic of Jade Cocoon revolved around capturing Mons and fusing them to try and pass on strong traits, spells, and techniques while weeding out the weak and less desirable ones. Then of course you can fuse your fused monsters again and again and again as much as you like.
Equestrian Legends has the Kirin. Half pony, half dragon. On a larger note, it's implied that dragons really sleep around and use life-altering magic to make sure the babies survive.
"No One Comes to Lupusville", a Real Ghostbusters episode with a Fur Against Fang theme, asks the question, "what happens when werewolves and vampires bite each other?" They wisely don't stick around to find out.
Fredrik K. T. Andersson (creator of the webcomic PAWN) loves this trope, though most of his pictures are NSFW. Said dragontaur even shows up with a potential daughter in law in one of those pictures: Click here (NSFW)◊