A "Langolier," as it was shown in the movie.
The Langoliers are creatures in the Stephen King novella of the same name. This novelle was included with three other novellas in Four Past Midnight released in 1990. They are depicted as ravenous fur balls with no legs and three mandibles. Their only form of sustenence would appear to be time. As time passes, they devour the universe that is left behind. The only way to come into contact with one is by being asleep as you pass through a time rift.
There is no known way to fight one. If they notice you, and they will notice you, your best hope is to escape using some high-speed transportation as an airplane, then find the time rift and escape into the present/future. The mode of transportation you escape in should be from the present/future you came from; if it was otherwise found in the "past," it will simply not work. You cannot scamper away on foot, as they will always catch up.
The monsters were also featured in a television movie based on the novella.
Etymology
Their name can actually be attributed to a Mr. Craig Toomey, the villain of Kings novella. As a child Toomey's father told him about a monster that would eat children who didn't behave, similar to the Boogyman, and that if he tried to "scamper" away, they would catch him. While stuck in the past, Toomey loses his sanity and tell stories about how the Langoliers were coming to get them.