When Teach was a child, he and his older brother would perform in plays in theater programs during summer camps, which made him interested in acting. When he was around eleven or twelve years old, he made a go at voice-over work for a children's network, but quickly ended it when a producer walked into the studio and told him that he sounded like a little girl. In high school, he enrolled in a four-year old drama program, where he also acquired skills as a set builder, which lead him to pursue a career as a carpenter.
After finishing high school, Grant did some group theater at the Carleton University, where he was studying psychology. He also entered into the theater program at the Ottawa University, but it did not work out, as he didn't like the roles he was given. He knew The X-Files was shooting in Vancouver and sold everything he had and got on a plane to start a new life there. After a series of black box theater productions, he booked his first audition, which was for the 1997 independent film Limp. This landed him a leading role opposite the late rock star Michael Hutchence. In 2005, he played one of the leading roles in the horror film Devour, where he acted opposite Supernatural star Jensen Ackles.
Grant is best known for guest starring as the Envoy super soldier Jimmy Desoto in the science fiction series Altered Carbon and the alcoholic Preston Riley in the drama series Damnation, as well as the recurring role of Scarhead on the horror drama series Van Helsing. He has worked most prolifically in television and is notable for his recurring roles on television series such as The Bletchley Circle: San Francisco, Supernatural and The 100. In 2019, he played the grown-up version of the murderous bully Henry Bowers in the supernatural horror film It Chapter Two.
- Acts opposite fellow Once Upon a Time actor Rose McIver on the iZombie episode "Eat a Knievel", where he plays a friend of a victim in a murder case investigated by Rose's character Liv Moore.
- Originally, his character on Damnation was going to die in episode two or three, but show creator Tony Tost was so impressed with Teach's performance that he expanded his character into a series-spanning role.
|Once Upon a Time: Season Five|
|"The Dark Swan":||"The Price":||"Siege Perilous":||"The Broken Kingdom":||"Dreamcatcher":||"The Bear and the Bow":||"Nimue":||"Birth":||"The Bear King":||"Broken Heart":||"Swan Song":|
|"Souls of the Departed":||"Labor of Love":||"Devil's Due":||"The Brothers Jones":||"Our Decay":||"Her Handsome Hero":||"Ruby Slippers":||"Sisters":||"Firebird":||"Last Rites":||"Only You":||"An Untold Story":|