Mount Katahdin is the highest mountain in the U.S. state of Maine at 5,269 feet. Named Katahdin, which means "The Greatest Mountain", by the Penobscot Native Americans, it is within Northeast Piscataquis, Piscataquis County, and is the centerpiece of Baxter State Park. It is a steep, tall massif formed from a granite intrusion weathered to the surface. The flora and fauna on the mountain are typical of those found in northern New England.
Katahdin was known to the Native Americans in the region and was known to Europeans at least since 1689. It has inspired hikes, climbs, journal narratives, paintings, and a piano sonata. The area around the peak was protected by Governor Percival Baxter starting in the 1930s. Katahdin is the northern terminus of the Appalachian Trail and is near a stretch known as the Hundred-Mile Wilderness.
In 1967, Mount Katahdin was designated as a National Natural Landmark by the National Park Service.
The mountain is commonly called just "Katahdin", though the official name is "Mount Katahdin" as decided by the US Board on Geographic Names in 1893.