Trapper Creek Wilderness is a federally designated wilderness in the Gifford Pinchot National Forest in southern Washington, covering 5,969 acres and nearly the entire Trapper Creek drainage. Its steep, rugged terrain of forested slopes, streams, waterfalls, and cascades shelters the only pristine anadromous fish habitat in the Wind River watershed and one of the few sizeable low-elevation old-growth forest blocks remaining in southern Washington. The area supports Roosevelt elk, black-tailed deer, black bear, spotted and barred owls, pileated woodpeckers, and goshawks, with cougar, bobcat, and pine marten seen occasionally. Primitive trails cross the wilderness, and Observation Peak is valued for its expansive views.