Stephen King's The Mist Wiki has a more comprehensive article on the same character. For it, see http://stephenkingsthemist.wikia.com/wiki/Ollie_Weeks
Ollie Weeks is a bachelor who worked as assistant manager at the Federal Foods Company supermarket in Bridgton, Maine. He appeared as a central character in the novella The Mist and its film adaptation, where he was portrayed by Toby Jones.
The Mist
Ollie is first seen working the counters at the crowded supermarket. After a power outage, he is working hard to satisfy the needs of the customers who are coming in to get last-minute supplies after a devestating summer rainstorm destroyed much of the town's property. However, the town's emergency air raid sirens blare and Dan barges in with a bloody nose, demanding that they shut the doors. At this time, a thick mist rolls through the parking lot and a large tremor shakes the store. At this time, the sirens abruptly stop and everyone wonders what is happening. They soon realize that there are creatures from another dimension inside the mist, that have been released when a group of soldiers at a nearby military base began trying to communicate with other dimensions. Ollie begins drinking on the job, and when Bud Brown, manager of the supermarket, threatens to fire him, Ollie calmly tells him off. Ollie is one of the only people, besides David Drayton, to keep his cool during the chaotic situation. Ollie is hinted to be a Vietnam War veteran in the novel, but in the film he is a competition shooter. This is why he predominantly uses Amanda Dumfries's Colt Magnum Carry .357 magnum revolver to kill several creatures over the span of the story. The other 70 supermarket patrons resort to listening to crazed religious zealot Mrs. Carmody, who promotes that the cactaclysm is the end of days and she promotes violent old testament teachings. After Mrs. Carmody demands that David's son, Billy, be sacrificed to God so the 'demons' outside don't kill them all, Ollie shoots her twice, once in the chest and then in the forehead, killing her. He then aims the revolver at everyone else and they make their escape from the supermarket, away from the scared and desperate patrons inside. Ollie is attacked by a gigantic creature and ripped in half during the escape, but as a dying act of good will, drops the revolver on the hood of the car so the remaining five survivors have a chance at survival.