Gladis was born in Houston, Texas. He was raised in Farmington, Connecticut, the son of a sales and marketing executive and a state worker. He graduated from Farmington High School in 1995. Inspiration for a life of acting originated from the time he spent volunteering for theater productions at Miss Porter's School, the internationally known all-girls school in town, where he knew male actors were needed. Most of his family is either Catholic or Christian, although his maternal grandfather was Jewish.