The drama stars Britt Robertson as Cassie, a girl who moves to Salem and discovers that she is a witch.
Zap2It reports that Harrington has now joined the cast as a guest star and will play Ethan, the father of Thomas Dekker's character Adam.
Harrington has previously appeared in shows including Dexter, Queer As Folk USA and Whistler.
Meanwhile, Snakes On A Plane's Emily Holmes has also landed a guest role in the project. She is expected to play Cassie's dead mother Amelia.
Secret Circle, which is being executive produced by Vampire Diaries showrunner Kevin Williamson, also stars Ashley Crow, Natasha Henstridge, Louis Hunter, Phoebe Tonkin, Gale Harold, Shelley Hennig and Jessica Parker Kennedy.
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