A native of Toronto, Canada, Adam O'Byrne began his career at The Stratford Festival of Canada where he was a member of the prestigious Birmingham Conservatory. In the 2006 season, O'Byrne played leading roles in LONDON ASSURANCE (directed by and starring the legendary and late Brian Bedford) and I HENRY IV (directed by the late Richard Monette). Other appearances included Miles Potter's acclaimed production of ORPHEUS DESCENDINGMEASURE FOR MEASURE, THE BROTHERS KARAMAZOV and THE WINTER'S TALE.

O'Byrne moved to Los Angeles in 2007 where he has continued to participate in North American theatre. He played Andrew Sr. and Calhoun in the world premiere of Alex Timbers' BLOODY BLOODY ANDREW JACKSON. He spent a season with Shakespeare Santa Cruz playing Berowne in LOVE'S LABOURS LOST (directed by Tony-nominee Scott Wentworth) and Roderigo in OTHELLO (directed by Tony-winner Pam Mackinnon). He has worked twice with ACT in San Francisco appearing in hit productions of THE HOMECOMING and ARCADIA. At Yale Rep, he appeared with Lupita Nyong'o in THE WINTER'S TALE, opposite TRUE BLOOD star Joe Manganiello in A STREETCAR NAMED DESIRE, and most recently, in the world premiere of Rolin Jones' adaption of MUCH ADO called THESE PAPER BULLETS. In 2015, the show played at the Geffen Playhouse in Los Angeles and The Atlantic Theater in New York. O'Byrne received praise for his portrayal of Don Best in the New York Times and the New Yorker magazine.

O'Byrne has had major recurring arcs as "Ryan Jackson" on the CBS sci-fi series EXTANT opposite Halle Berry, as "Nate Tyler" on the Amazon Studios drama BOSCH opposite Titus Welliver, and as "Kaleb Peat" in the second season of TNT's MURDER IN THE FIRST, as well as a recurring role in the final season of AMC's HELL ON WHEELS. He was the series regular, "Leroux", on Rolin Jones' AMC pilot KNIFEMAN. Other television credits include guest spots on NBC's GRIMM, on the hit CBS series COLD CASE and NCIS as well as VEGAS and CASTLE. He played the villain "Ravin" opposite fellow Canadians Carly Pope (POPULAR) and Brandon Jay McLaren (THE KILLING, GRACELAND) in the SyFy Original YETI. O'Byrne had a significant supporting role in the Indie Western DEAD MAN'S BURDEN, directed by Jared Moshe and he appears in the 2015 Elliott Lester thriller SLEEPWALKER, starring Ahna O'Reilly and Richard Armitage. 

A graduate of Yale College, O'Byrne matriculated immediately to Yale School of Drama where he began his ongoing collaboration with the Pulitzer- and Emmy- nominated Rolin Jones. In the Spring of 2002, O'Byrne appeared as Dr. Yakunin and others in the first production of Jones' play THE INTELLIGENT DESIGN OF JENNY CHOW. Since then, O'Byrne has appeared in a Jones episode of THE UNITED STATES OF TARA, as well as the aforementioned KNIFEMAN and THESE PAPER BULLETS. Additionally, he produced the award-winning short film adaptation of Jones' play CHRONICLES SIMPKINS WILL CUT YOUR ASS that played in more than 10 film festivals around the world. In April of 2015, O'Byrne, with Jones, became a founding member of the production company, NEW NEIGHBORHOOD (www.newneighborhood.net).  O'Byrne graduated YSD in 2004 and was awarded the Herschel Williams Prize given annually to the graduating actor with outstanding ability.

O'Byrne lives in Los Angeles with his wife, Laura Smolowe, a partner at Munger, Tolles, and Olson, and their two daughters.