Kildar is a military fiction thriller novel by the author John Ringo. It is a sequel to his earlier book Ghost - the first in the Paladin of Shadows series - about the adventures of former US Navy SEAL Mike Harmon (A.K.A. Mike Jenkins, Ghost, and 'Ass-Boy Two') as he engages in combat with various terrorist groups.

In Kildar, he is lying low after his actions in France, wandering the less populated areas of the Caucasus. It is in a remote area of the country of Georgia where he discovers the Keldara: a group of peasants with intriguing customs whom he believes will make a suitable militia to counter raiders from Chechnya who have been known to frequent the area.

Mike buys the local castle and, as such, becomes known by the ancient title of Kildar, lord of the local families. He purchases equipment to build up the local infrastructure and hires some of his allies from his military days as trainers.

However, upon witnessing one of their seasonal festivals, he realizes that they are in fact a remnant of an ancient group of Viking warriors, the Varangian Guard—an elite group of personal guards to the Byzantine Emperor, with warrior prowess comparable to the Gurkhas or Kurds. He then raises his sights: Instead of training them as a militia, he plans on turning them into a company of commandoes.

This is wildly successful, and after only basic training a group of Keldara are able to defeat a group of Chechen raiders three times their number. Convinced thus, he has them issued uniforms and shoulder patches defining them as the "Mountain Tigers".