Alien big cat is the more usual term here.
Phantom cat suggests spectral cats, which is slightly different. A lot of ABC fans consider them flesh and bone. As pointed out in the article, some have been very real and actually captured.-Albannach (talk) 16:34, 22 April 2013 (UTC)
There are spectral cats  - and there is Kitten Kong. And there were probably a few cases of 'little kitten surprised me' becoming a great big beastie in the retelling, 'what would happen if the Tower lions and heraldic beasties escaped into the wild, and the other usual suspects. Anna Livia (talk) 12:45, 14 February 2018 (UTC)