And parodied in Ansem Retort; when Zexion insists that Hercules be one of these, Hercules replies that his top half is centaur and his bottom half is human.
Gannet from Avialae starts unexpectedly growing wings one day and later learns that it's because his mother belonged to a Winged Humanoid species hidden from human society.
Cassiopeia Quinn: Humans can interbreed with Xerrans to produce viable hybrids, and numerous characters — such as Madison and Kettlehead — are part Xerran themselves. In point of fact, almost every Xerran alive has at least traces of human ancestry by the comic's present.
City of Blank: If a human and a blank who's developed enough after taking someone's face procreate, it's possible for their children to be human-blank hybrids. Hybrids have sentience and can communicate via sign language.
In Clockwork hybrids are feline-featured humanoids (although small subsets of hybrids exist, such as insects). They are almost indistinguishable from humans, aside from their larger size - although in extremely rare cases, hybrids are born with features such as tails, antennae, etc. Leonardo von Ostrand, Arcadia's admiral, is one such case.
Lorenda is half-demon mare, half... cow. This essentially makes her a carnivorous cow, but to the chagrin of her demonic mother, she only eats evil creatures — like door-to-door salesmen! Now she's grown wings... but they're hilariously tiny and useless. Her demon mom is embarrassed.
Also Jyrras, whose father is a pureblood Kangaroo Rat, but his mother is only half that... the first half.
Creator Amber Williams has created a side comic arc to describe exactly what species of furre can inter-breed and exactly what will result from such a breeding.
In Dragon Mango, Mango herself was the first, but not the last, child of a human and a Dragonslayer.
Also, Peaches: Human mother/Ogre father. This turns out to be the genetic makeup of every female ogre.
Mara from Elf Blood is half dark elf, half human. According to TKO, there aren't that many half-elves, most likely to do with the hidden nature of the elves.
Carlita Delacroix is also half-human. Her other half is feline spirit incarnum (fleshy forms of natural spirits).
And the whole reason that the Errants were formed was because it was found that Elves could breed more easily with Humans than with other Elves for some unknown reason. It was only decades later that Errants suddenly started going bad at random.
Part of the appeal for a human lover was that elves idolized the concept of losing a lover before you grew tired of each other, so you could remember them for how much you loved them. Humans, with their comparatively short life spans, were very well suited for this.
First-generation hybrids are usually healthy. But repeated interbreeding between Errants can cause defects, some very severe. Exacerbated by the fact that Errants tend to be 'stuck' in their original 'mold', so it is nearly impossible to permanently heal congenital defects.
In Fairy Dust, all humanoid races can breed with most others, and humans aren't shy to do so. One extra character appears to be half troll, with a few scars hinting that he had surgery to look more typically human.
Fans! deconstructs the trope with Zaha, an engineering student who was merged with her pet cat in a freak accident, and ended up a Cat Girl. She has to take several kinds of medicine daily just so her body can function, and longs for humanity. Eventually she exchanges bodies with a member of Furry Fandom, who is thrilled.
Dan at least explored some less glamorous possibilities — in more or less ideal circumstances of the Second Life Alternate Universe, a lot of awkwardness and heart-breaking happened just because Archie inherited anatomy mostly from human ancestors and psychophysiology mostly from tele-empathic shapeshifting androgynous Uryuoms. Vlad was a broken result of the same progeny-shaping experiment as Grace.
There is also Adrian Raven, who is half human/half immortal. This grants him great magical ability, although not nearly at the level of a true immortal, extended life (uses magic to appear old), but also limits how much he is allowed to participate in human affairs. He can teach and help fight magically based threats, but can't fight in human wars.
In Homestuck, Jade prototypes Dave's sprite with a crow he accidentally killed while trying to retrieve his copy of Sburb, which is later on prototyped with a Dave from a doomed timeline who retains the wings and feathery body of the crow. Jade's dream self becomes a half-human half-dog first guardian after she prototypes her sprite with it to ressurrect it, at the cost of wiping Becquerel from existence. She gains dog ears, becomes malicious towards cats and occasionally barks, traits which Jade inherits when they merge and ascend to god tier.
In Hominids Comic, the Neanderthal Zona was impregnated by a young Cro-Magnon named Icari. She is currently carrying their hybrid child or children as it is yet to be confirmed whether she's pregnant with twins or not.
In the Hotblood! universe, this is deconstructed. If a human/centaur couple defies societal norms and gets together, any attempt at having biological kids are hampered by the mechanics first, but if conception somehow takes place, the pregnancy will be full of complications and biological defects.
Commonplace in I Don't Want This Kind of Hero, ranging from people who look fully human/animal but have inward characteristics of both and the expected outwardly mixed types. It's not just animals either: one minor character is a Half-Human Hybrid of an action figure come to life.
Martin from Ignition Zero is half-faerie. His mother had an one night stand with his father (the Holly King), who was disguised as a human and disappeared afterwards. He passes as human except for a glow in his eyes, which is why he wears sunglasses. He received Fantastic Racism from faeries for passing as human. When his half-faerie heritage is revealed, Martin learns to stop living a double life and accept both sides of his heritage equally.
The genetic cocktail that spawned Molly and Galatea in The Inexplicable Adventures of Bob! did contain some human DNA, albeit not much. In fact, it was Jean's, making her their biological mother, just "a little bit."
In Juathuur, Thoss and Thlassa are half-solluu (fish people) and half-juathuur (humans with powers).
And then there's Kevin & Kell. The central family is itself several mixed species, and while the setting has a bias against interspecies romances, it really is more inter-diet relationships (carnivore vs herbivore vs insectivore). As far as strict species goes...
Rudy Dewclaw: half grey wolf, half red fox. Lives and looks like a wolf.
Fiona Fennec, his girlfriend: half red fox, half fennec. Lives as fox and fennec, and aside from an ethnic pride group, no one cares.
Coney Dewclaw, his half-sister: half grey wolf, half rabbit. Rabbit looks, wolf appetite.
Lindesfarne Dewclaw, his adopted stepsister: former human, then hedgehog, then talked into being a porcupine, then realised is a hedgehog, dating a bat. 'Diaper a flying hedgehog', indeed.
Corrie Dewclaw, Rudy's cousin. Half grey wolf, half sheep. Lives and looks like a sheep, but don't get her mad.
Francis Fennec, Fiona's new half-brother. God knows what he is—the geneticists can't figure it out either. Looks like a ball of fluff. Father is a fennec, mother's a former human, current rabbit with the old human preferences. Turns out, he's human, due to Danielle being originally human. Lindesfarne theorizes the same would happen to her children.
And there's some minor mixes, like a half-moth half-firefly who orbits himself, or the illicit baby between a turtle and a weasel. Confused yet?
There is a bit of a subversion though: as revealed on Lindefarne's blog, human genes are dominant — no matter what the offspring of a human or former-human relationship looks like at birth they will always become completely human within a few months. This is based off of the discredited theory that people "evolve" from single-celled organisms, to fish, to reptiles, to mammals, to monkeys, and so-forth, all while they're still in the womb, but it certainly makes for a few interesting plot points.
Kubera has "Halfs", who are humans with 50% or more sura blood. Halfs have four times the lifespan of pureblood humans and are relatively balanced in terms of power: they can use transcendental attacks but not magic, and are physically stonger than purebloods but are susceptible to emotional resonance.
Benn'Joon, the priestess from Looking for Group. If we go by appearances, she's a Blizzard troll...but she's definitely not one of the setting's trolls. Her race is never out-and-out stated; she's referred to as a "female of unknown pedigree." And speculating about her ancestry on any appropriate forum will lead to heated debate.
Although according to a recent comic, it appears that she may be at least Half-Elven. Assuming her mother is indeed Captain Tah'Vraay.
Lovely Lovecraft: Presumably, the bus-driving Innsmouth denizen in the first few pages is a human/Deep One hybrid.
A Magical Roommate has an interesting example in the case of X and Alexis. Their mother, who was born a black fairy, shapeshifted to a human form she kept for her pregnancy... well, for the most part. This has made the twins roughly ninety-eight percent human and two percent fairy.
MSF High: Most demi humans are these on varying human to animal ratios, with domestics being on the human end of the scale and martials being on the animal end.
My Best Friend Marneao: Thousands of years ago, after Yahveh and Lucifer found the first human, there was peace between the angels, demons and humans. Demons, being creations of Lucifer, found they were able to have relationships with humans. The protagonist Marneao, Miltch and Medina are offspring from relationships between the two species.
The Noordegraaf Files: Possibly Violet, if the alt text introducing her is taken to its logical extreme. She does have purple eyes.
Sara Greenhilt: I want to be able to hear the pitter-patter of little feet — or the whoosh-whoosh of little wings, as the case may be.
A literal-minded orc also lampshades the assumption that "half-X" assumes the other half is human. "chief grukgruk half orc too. other half, also orc."
Enor the bounty hunter is a Half-Dragon Half-Ogre: Half blue dragon, half ogre... or one quarter ogre, one quarter human, it's not entirely clear.
Girard Draketooth's surname was revealed to have originated from him being the son of a half-dragon. Unfortunately, his dragon grandfather was a Black Dragon of a certain family tree... Vaarsuvius didn't strictly know any of that when casting Familicide, but admits that "the propensity for both humans and dragons to breed outside their species is well-documented", and that they should have realized that something like this would happen.
In Rogues Of Clywd Rhan, one of the main characters named Kel is a half fairy/human hybrid whose biological father is a human and biological mother is a fairy named Maghreid. Vigdis is a minor character in the same web comics as well as a fellow half fairy/human hybrid of Kel whose father and mother are of the same species as the latter's.
The amorphs from Schlock Mercenary are capable of creating offspring with any species, although the children are identical to normal amorphs. An offer to make children to Breya by Schlock causes a lot of squick reactions, but although she turns him down, they are able to talk about it in friendly terms after the humans realize amorph reproduction doesn't involve sex.
Schlock himself apparently has a human grandmother.
For explanation, the amorph would imprint desired personality traits from their partner onto an asexually-produced amorph spawn.
In Scurry And Cover, Beasts can cross-breed with humans. The protagonist is a 1/4th rat girl.
Parodied in a Sev Trek cartoon about what characters might appear in the next Star Trek series. The winner was: a Klingon/tribble hybrid torn by hatred for its two sides and constantly annoyed by questions of how its parents got together to mate.
It's a plot point in Spacetrawler that humans are genetically intercompatible with the psychic alien slave-race called Eebs. Human material is used to genetically engineer a hybrid subspecies of the latter with more independence, and no psychopathic tendencies or psychic powers.
A more conventional example appears near the end of the series. Dmitri (go figure) and the Eeb Red-9 have a drunken one-night stand, and Red-9 gets pregnant. On the last page of the comic, Dmitri moves in to help raise the child, which is never seen.
Cade Masters from Twice Blessed is 3/4 human, 1/4 elf. (His father was a human and his mother a half-elf).
Underling leads one to believe this of Lazarus, though he ends up not being so.
In Wapsi Square, Shelly is a human/sphinx hybrid. This gives her most of the powers of a sphinx, but with a human lifespan. Later revealed to be a human/sphinx/Titan hybrid (her mother was lying).
The Weave has Changelings, which is the term for children who have a human and a fairy parent.
Wyrmspawn in Wizard School is a half-dragon, half-human hybrid leading the Dragonkin.
In Yet Another Fantasy Gamer Comic, the character of Glon is a (much put-upon) half-human half-orc. There are also half-brothers Cadugan and Taidor. They share a human mother, but Cadugan's father is an elf (Prince Glitterbranch of the Wood-Elves, no less!) and Taidor's father was a Satyr.