Marmot is the character in the TV show Franklin. He/she is voiced by Bryn McAuley, who would later be the voice of Harriet.
Marmot is from Cedar Brook School, and in "Franklin Has the Hiccups," he/she is that school's chess champion. When he/she gets nervous, his/her stomach hurts.
It is never mentioned if Marmot is a boy or a girl.