Carl L. Poser was a guide who worked at Knollwood, at cottage 3. He came to the area with tuberculosis. He was a friend of the Marshall brothers. On August 1, 1918 Poser hiked up Whiteface Mountain with Herb Clark, George Marshall, and Bob Marshall as the two brothers and their guide began the journey to climb all the Adirondack Mountains over 4,000 feet. Poser did not hike all 46 high peaks but he does have the distinction of being with Clark and the Marshall brothers as they began their quest on the way to becoming the first ADK 46ers. He was named on the published list of "Registered Guides in New York State" in 1942.
A brick at the Saranac Laboratory Museum has been dedicated in honor of Carl Poser.