Mount Regan, Mountain summit in Sawtooth Range, Idaho.

Mount Regan is a 10,190-foot (3,110 m) peak in the Sawtooth Range, on the border of Boise and Custer counties within Sawtooth Wilderness. It stands at the southern end of Sawtooth Lake, 1.9 mi (3.1 km) west of Merritt Peak, its line parent. Trailer Lakes and Regan Lake lie northwest, and the Trail Creek Lakes west of the peak.

Mount Regan is named after Timothy Regan, a pioneer who lived first in Silver City and later in Boise. The sources record no first ascent, so the 1934 climb attributed to Robert and Miriam Underhill is unsupported. The peak lies on the Boise–Custer county line in the Sawtooth Wilderness, 1.9 miles west of Merritt Peak, its line parent.

The peak is named after Timothy Regan, a pioneer who lived in Silver City and later in Boise. The name is the main cultural trace the sources record for the mountain; no climbing tradition or first-ascent account is documented.

The peak is accessible via Iron Creek Road leading to the Iron Creek campground and trailhead. Visitors should prepare for steep, exposed terrain and changing mountain weather conditions.

The mountain offers four distinct climbing paths: Southeast Ridge, Lower East Face, North Ridge, and Northwest Ridge, each presenting technical challenges.