The Mullen Fire was a wildfire that burned over 176,878 acres (71,580 ha), 28 miles (45 km) west of Laramie, Wyoming.

On September 30, it spread into Jackson County, Colorado.

It burned close to the Rob Roy Reservoir and Platte River Wilderness.

At that time the fire was initially believed to be human-caused, however details remained limited as it was early into the investigation.

Cooler temperatures and precipitation were able to slow the fire's growth.