Continuing with hybrids.
Coydogs (coyote x domestic dog) and wolfdogs (wolf x domestic dog) are widely documented and bred (mostly by irresponsible backyard breeders sadly). However, one hybrid that you would think exists, bobcat x domestic cat, has never been officially documented or determined via DNA. All evidence of such is anecdotal and circumstantial.
There are a select few cat breeds, like the Savannah Cat, that were produced by crossed small exotic cats (like servals) with domestic cats, but the bobcat cross has yet to be seen...
On the same note, wolf x coyote hybrids are not only known to exist, but have become significantly more common in recent years.
The extirpation of wolves from most of North America south of the boreal forest has left a huge ecological gap, which the opportunistic coyotes have rapidly filled in the past 50 years. Now even Chicago has a very stable population of coyotes which get a surprisingly large amount of their calories from bringing down fucking white-tailed deer. As the protected wolves have slowly (and oftentimes secretly - there's definitely areas in Maine and the LP of Michigan, for instance, where wolves are 100% present but where their presence has been stoutly denied by DNR-types who don't want to spark off the political controversies that the return of wolves inevitably creates) also spread back to the south and east, they've interbred with coyotes.
The hybrids are noticeably more dangerous than either wolves or coyotes. Wolves, see, are extremely skittish around people. By many accounts, the general response of a North American wolf to the presence of people is to get the fuck out of the area. I've seen speculation that this is an evolutionary adaptation to historically very strong persecution of wolves in North America, but this is unproven. What is pretty well-established is that wolf attacks in North American history are
extremely rare. Coyotes, OTOH, as sneaky little bastards, are much less afraid of people. There's a number of coyote attacks every year - mostly in California, where stupid suburbans who have no respect for the fact that wildlife is, well, wild live in areas immediately abutting roadless wilderness zones - but if you know what you're doing they're not much of an issue because they're small, cowardly critters, weighing maybe 40 or 50 pounds tops.
But when you cross a coyote with a wolf, sometimes you get a beast with the greater size of a timber wolf and the lack of fear of humanity of a coyote, and they've been caught occasionally causing problems as far east as New Brunswick. It's just one more reminder that, despite the efforts of both conservationists who want everything left Exactly As It Was, and industrialists who want the inhuman paved over and herbicide'd into submission, nature'll end up doing weird and dangerous things we can't predict.
