Krolp

"They weren’t invulnerable. Humans could kill them. Unless somebody got amazingly lucky, the usual cost was about two armored divisions and all their matériel for one Krolp."

- Harry Turtledove, Vilcabamba

The Krolp are a race of "centauroid" aliens appearing Harry Turtledove's short story "Vilcabamba". The Krolp are larger than a horse, with gray skin and heads similar in appearance to a jack-o-lantern and mouths lined with a sharp edge, but no true teeth, and large, glowing, cat-like eyes. The Krolp also have been described by humans as smelling like Limburger cheese.

The Krolp invaded Earth in the 22nd century, and quickly overwhelmed humanity's defense, easily shooting down or disarming the nuclear weapons used against their initial invasion forces. The US and Canada joined together to fight the Krolp, but their efforts were for not. The Krolp were not invincible, but it took large amounts of human resource to kill just one of them, to the point that two division of men and materiel were lost for every Krolp soldier killed. The Krolp quickly took control of most of Earth. After the Krolp conquest, the Russians, Chinese, and Americans joined forces and rose up. However, only about 50 Krolp were killed before the rebellion was crushed. After the uprising, the then U.S. president escaped to the Rocky Mountains, and, after negotiating with the Krolp, the US (now reduced to the area around the Rockies and Wasatch, were allowed to exist as an independent enclave The joint-US-Canadian nation persisted for another 50 years, until the Krolp discovered silver deposits under Utah, and demanded they be allowed to mine them. Knowing how destructive Krolp mining techniques were, as they had wiped out all of Spain, the US president, Harris Moffat III, launched one final uprising, which failed and was crushed in three days.

Krolp technology is centuries, perhaps millenia beyond that of humanity. Humans can use their weapons, but have no idea how they work. The best guess is that the Krolp are capable of manipulating gravity and strong and weak nuclear forces as easily as humans can manipulate the electromagnetic spectrum. They also carry highly destructive weapons of an unknown nature, possibly some sort of energy weapon.

The situation of humanity and the Krolp was intended as a reference to the Inca city of Vilcabamba, the last independent enclave of Incan resistance, which was crushed in 1572 by Spanish Conquistadors.