Colter is an English surname that means "colt keeper" or "horse herder", given to a man who looked after young horses. Americans know it from John Colter, a member of the Lewis and Clark expedition who later explored the Yellowstone region as a mountain man. The name entered the US top 1000 only in 2019 and has climbed at a remarkable pace, from number 969 that year to number 157 in 2025.