Here's one of the creatures in my world:

They are similar in size to a tiger, with dark brown fur and black stripes. They have large paws which allow them to run across snow without sinking in very far, though they prefer to stay underground.

The stav has a large head set on great shoulders with a short, thick neck. The head has the most discerning features: large, dark green eyes; deer-like ears that can hear very well, and a stub nose.

The mouth is perhaps the most discernible feature of all: it has a large mouth with many sharp teeth and the stav has the ability to open its mouth quite wide. Its front teeth stick out of its mouth: two on the top and two on the bottom. The top two center teeth are long and curve down past its lower lip. The teeth on the bottom (one to each side of the center teeth) also stretch up past the upper lip. These teeth, combined with the ability to open its mouth widely, give the stav an easy way to incapacitate their prey.
If bitten, it is nearly impossible to free yourself from the teeth unless the bitten appendage (foot, hand, arm, etc...) is amputated. This can happen either by the stav's tearing or by human intervention (with a sharp knife, sword, etc...)

The stav have no other ways to incapacitate their prey except for their teeth (no poison or whatnot). They also travel in groups of five or six with two males per group and around four females.

Any thoughts?

These sound cool! Do they have claws? How fast can they run? How long/far can they run? Do they make any sort of noises specific to their species? What do they prey on?

Nice. Why do they prefer to stay underground? Do they live in caves?

(I have tiger-inspired creatures, too: viewtopic.php?f=13&t=5665)

They don't have claws, because that would weigh their paws down too much (remember, stavs have snowshoe like paws). Stavs prefer not to run too fast because they mostly live in underground tunnels and speed can cause you to run into things. However, they can run fast for a short distance if they are above ground.

The reason they remain underground is because their eyes are large, useful for seeing in dark places. This causes the sun to hurt their eyes, which is why they will only leave their underground tunnels at night. However, they will travel above ground on the top of Frostbite Mountain (a mountain the peak of which hardly ever sees the sunlight).

Their main prey is mountain goats or humans. Their main predator are marfogs (a dragon-ish creature). Marfogs can fly, which is another reason why stavs prefer to remain underground.

Cool!

What do they eat? Do they make noises at all, like when attracting a mate or for defensive purposes?

The stavs already have a mate, because they hunt in groups. Stavs have free choice of any of the female in the group.

Their sounds are usually limited to chuffs and puffs of air.

They eat mostly mountain goats and the occasional human, but sometimes will prey on each other if there is not enough food. Each group of stavs will hold as their territory an area of about three square miles. However, they will move if there is not enough food and generally get along with others of their kind as long as they do not meet. Even if they find traces of other stavs on their territory, they will not chase after them, choosing to wait until confrontation by the other party. Even with confrontation, the stav will merely scare the others off, rather than kill them.

This 'lone wolf' mentality keeps the stavs from killing each other, but it also keeps them from protecting each other if a large enemy attacks.

Very cool. It sounds like these are a good way to add a sort of "natural menace" to some of the places in your story world.

These guys sound neat. I personally have a fondness for great cat-like creatures.... XD

Can Stavs be tamed, or has anyone ever tried?

Stavs have a tendency to eat humans, so most humans don't try to tame them. They might be tamable, but nobody has ever tried.

The top teeth hold your flesh in from the top, and the bottom teeth hold it in from the bottom. If you move it one way, it is still stuck on the other teeth. Does that make sense?

So are their teeth like sharks' teeth in that moving the bitten appendage would result in its amputation?

No, but if the stavs pull hard enough, the limb will amputate. Or the human (if the victim is human) can amputate the limb to save themselves from the stav. For the stav will stay with the limb (easy meat), rather than chasing after the human.