Ultra-cats

In the 1960s, the Soviet Union as part of their cold war arms buildup began genetic experimentation, resulting in the creation of Ultra-cats. It took years of work, and many revisions of cats, but the final spec for ultra-cats basically read like this: Minimum of 2200 pounds, at least 6 foot high at the shoulder, with strength roughly equivalent to 10 Siberian tigers. For combat certification, each Ultra-cat had to bite through a 2" thick steel bar, rip the tracks off of a T-68 combat tank, and run at least 95mph, although elites could easily top 150.

The problem they had with them, though, is they were too hard to control, and too strong to effectively contain. Many trainers were eaten or gored, Ultra-cats during war games were sometimes known to do more damage to their allies than their enemies, and several escaped custody.

The program was eventually scrapped and all the animals euthanized, except for the few that escaped. They were long thought to be dead, but recently a village in Siberia was devastated by a large, cat like creature the locals have dubbed "ha natma tumbisi" or "That which swallows man whole" Russian officials have had to cover this up, because the program is still classified.