Phantom cats

Phantom cats or alien big cats (ABCs) are terms generally (see below) referring neither to cats from outer space nor actual phantom cats, but to alleged big cats found outside of their territorial range. The explanations for their sightings ranges from the sensible, such as escaped zoo creatures, military mascots, and pets, to the absurd, such as there being a population of hybrid big cats in Britain. Scientists point to the improbability of a breeding population of big cats surviving and feeding themselves undetected in the UK, but occasionally big cats do escape from captivity.

Actual occurrences
Given the number of zoos in the world, and the fact that big cats are a common feature in said zoos, one escaping at some point is inevitable. Notable occurrences have occurred in the UK with escaped pumas and lynxes. It has even been suggested that the was in fact a lion, not a wolf as was reported at the time.

The woo
As with many things in cryptozoology, whenever there is something sensible, there is also something outlandish. In the case of alien big cats, the idea is that the cats in question are in fact relictual populations from the last ice age. And, of course, there are people who believe that the cats are indeed paranormal or perhaps shapeshifters. A notable film treatment of the subject is the movie Cat People.

Felicity the puma
Felicity was captured at Cannich near Inverness in 1980. She was very tame and hence probably an escaped pet. She was rehomed in a wildlife park, where she died in 1985 and was stuffed and moved to Inverness Art Gallery and Museum.

Beast of Bodmin Moor
The Beast of Bodmin Moor was a panther-like creature reportedly seen several times in Cornwall in southwest England from 1978. Scientists pointed out that there wasn't enough food for a breeding population, but there were various rumours about animals released into the wild. A leopard skull was found by the River Fowey in 1995, but examination demonstrated that it had probably been imported to the UK as part of a leopardskin rug rather than a live animal. A government report found no evidence of an actual big cat. It was reported in 2016 that animal keeper Mary Chipperfield had let three pumas go into the wild around 1980, following the closure of Plymouth Zoo nearby, although such claims appear to be only hearsay.

The Beast of Cricklewood
A Eurasian lynx (also known as the Beast of Barnet) was caught in Cricklewood, north London, in 2001, sedated by a vet from the London Zoological Society.

The Beast of Gévaudan
This was a mysterious animal that terrorized the province of Gévaudan in France in the 17th century. Though at the time it was thought to be a wolf or part wolf, its behavior was unlike that of wolves. Modern research has suggested that it may instead have been a lion that escaped from a nobleman's private zoo.

Ruokolahti Lion
Reports of a female lion moving around in the municipality of in southeastern Finland caused a sensation in the country during the summer of 1992, despite the scarcity of hard evidence to support its existence. Initial reports suggested that a train or truck transporting circus animals could have suffered an accident across the nearby Russian border shortly before the lion reports started, although Russian authorities had no record of such an incident occurring. A circus without a warrant for keeping animals or a private household with exotic beasts have also been suggested as the origin of the lion.