Marquand was born in Fort Collins, Colorado. His initial foray into acting began at the age of nine when he played a small part in a church play. Soon thereafter, he joined the Boy Scouts of America and began impersonating celebrities at campfire ceremonies.
He graduated with a BFA (Bachelor of Fine Arts) in Theatre Performance from the University of Colorado at Boulder. After college he moved to Los Angeles and quickly garnered attention in several film and television projects.
- LA Forensics
- Love Sick
- Saturday Night Special
- Sex & Los Angeles
- A Lonely Place for Dying
- The Inappropriate Behavior of Our Alleged Loved Ones
- Mad Men
- Phineas and Ferb
- The Impression Guys
- Spare Change
- Avengers: Infinity War
- Ross frequently pursues roles that require him to alter his voice and appearance considerably.
- He starred alongside Danai Gurira in Avengers: Infinity War.