SNOW LEOPARDS

Real Name: Issa (and two brothers) Koblev

Identity/Class: Human mutants, Russian citizens

Occupation: Enforcer

Affiliations: Yi Yang (mistress);
    former student under Professor Phobos at the Super-Soldier School;
    possibly trained alongside Darkstar, Ursa Major, and Vanguard, and other former students of Phobos

Enemies: Black Widow (Natasha Romanoff), Night Raven, Ivan Petrovitch

Known Relatives: the three are apparently brothers

Aliases: None

Base of Operations: Formerly Yi Yang's Siberian refuge (Xanadu), and its predecessor the Super-Soldier School;
    formerly the Siberian wilderness

First Appearance: Fury/Black Widow: Death Duty (February, 1995)

Powers: The Snow Leopards had the standard feral cat-man powers: superhuman strength (enhanced human to Class 5), speed, endurance, agility, olfactory (smelling) senses, night vision, razor-sharp claws, etc. They were utterly devoted to Yi Yang.
    Issa Koblev demonstrated normal human intellect and speech, while his two brethren did nothing but snarl. It is unknown if they simply lacked his education, or if there was more to it.

History: (Fury/Black Widow: Death Duty (fb) - BTS) - Issa Koblev and his two brothers were apparently born with their mutant abilities and appearance. They were either abandoned by their real parents, or taken from them by the Russian government. They became a wards of the state and were sent to the Super-Soldier School, where they were trained under Professor Piotr Phobos. When the Project was shut down, they and many of Phobos' students were left behind--left to rot in the middle of the frozen wastelands of Siberia.

The Snow Leopards went out on their own, living in the frozen wilderness, among the wild animals. Eventually they were discovered by Yi Yang, who took them in. She became Issa's teacher, and his lover. He became enthralled by her. They made Phobos' forgotten citadel their own, renaming it Xanadu. However, Yi Yang's old nemesis, the Night Raven, eventually located her in Russia, and began to interfere with her plans anew.

(Fury/Black Widow: Death Duty)-The Night Raven continued to track down Yi Yang, working alongside the Black Widow. Yi Yang dispatched the Snow Leopard (Issa) to engage them. He captured the Black Widow's friend and ally, Ivan Petrovitch, in order to draw the two to him. As they battled, the Night Raven briefly gained the advantage over the Snow Leopard, at which point Yi Yang blew up the entire warehouse, in an effort to destroy her eternal foe. Her enemies escaped the explosion, but the Snow Leopard was apparently killed.

When the Black Widow and Night Raven made it to Xanadu, Yi Yang revealed the existence of two more Snow Leopards. These two attacked the heroes, and one nearly decapitated the Night Raven, but both ended up getting tossed into this raw energy power core (made from the energies siphoned from mutants by Phobos--I'd tell you to go read it, but GOOD LUCK finding it!).

Comments: Created by Cefn Ridout and Charlie Adlard.

A lot of assumptions are made in the history. Ilsa's brethren may not have been trained under Phobos. They were only seen alongside Yi Yang after Ilsa's death, when she stated "Issa Koblev was not an only child."
Given the limited glimpse, and the behavior of his brethren, it is entirely possible that they were creations of Yi Yang, mutated based on testing of Issa--meaning that her comment was more metaphorical. That's how I originally took it, but now I'm not sure.
--Anyway, I'd consider Issa as the Snow Leopard, but either the last two, or all three could be the Snow Leopards.
"Ah, it's a moo point. You know, a cow's opinion. Who cares? It's moo"--Joey Tribiani, from Friends

The name Xanadu is an actual place on Mongolia used in the poem by Cole, "Kubla Khan". Marvel (and that movie with Olivia Newton-John) all take the name from there. Courtesy of John McDonagh, here's a link that gives you more detail: Xanadu

CLARIFICATIONS: The Snow Leopards have no known connection to:

• Siberian Tiger, also a Russian cat-like mutant, who served with Yuri Garnoff, @ X-Factor Annual#1
  --although it would be an exceptionally easy connection to make.