TELEVISION:
| Year(s) | Title | Role | Notes |
| 2001 | So Little Time | Senior High School Student | Episode: “Rules of Engagement” |
| 2002–2006 | Alias | Julian Sark | Main/Recurring Role; breakout performance |
| 2004 | CSI: Crime Scene Investigation | Travis Watson | Episode: “Crow’s Feet” |
| 2005 | Charmed | Count Roget | Episode: “Show Ghouls” |
| 2005 | CSI: Miami | Brian Miller | Episode: “Felony Flight” |
| 2006 | Deadwood | Infantryman | Episode: “The Catbird Seat” |
| 2007 | Grey’s Anatomy | Jim | 2 Episodes (Spin-off pilot) |
| 2007–2010 | Heroes | Adam Monroe / Takezo Kensei | Main/Recurring Role |
| 2009 | Lie to Me | Staff Sgt. Russell Scott | Episode: “Moral Waiver” |
| 2010 | 24 | Josef Bazhaev | Recurring Role (6 episodes) |
| 2010 | Warehouse 13 | Jonah Raitt | Episode: “Where and When” |
| 2010 | Undercovers | Matthew Hunt | Episode: “Assassin” |
| 2010–2017 | The Vampire Diaries | John Gilbert | Recurring Role (13 episodes) |
| 2011–2016 | Once Upon a Time | Victor Frankenstein / Dr. Whale | Recurring Role (15 episodes) |
| 2012 | House | Bill Koppelman | Episode: “Nobody’s Fault” |
| 2013 | Arrow | Cyrus Vanch | Episode: “Betrayal” |
| 2013 | Necessary Roughness | Troy Cutler | Recurring Role (8 episodes) |
| 2013 | Criminal Minds | Anton Harris | Episode: “To Bear Witness” |
| 2015 | Stalker | Darren Tyler | Episode: “Love Hurts” |
| 2015–2019 | iZombie | Blaine “DeBeers” McDonough | Main Role (Series Regular) |
| 2016 | Comedy Bang! Bang! | Loki | Episode: “Kaley Cuoco Wears a Black Blazer…” |
| 2020 | The Magicians | Visigoth Overlord Terence | Episode: “Magicians Anonymous” |
| 2020 | Roswell, New Mexico | Travis and Trevor | Episode: “Sex and Candy” |
| 2022 | Magnum P.I. | Ray Nasano / Kidnapper #1 | Episode: “Close to Home” |
FILM:
| Year | Title | Role | Notes |
| 2002 | The Source | Booji | Credited as David Holt |
| 2005 | Circadian Rhythm | Garrison | Action/Thriller |
| 2006 | Left in Darkness | Donovan | Horror; Direct-to-video |
| 2007 | ELI | ELI | Short Film |
| 2009 | Into the Blue 2: The Reef | Carlton | Action; Direct-to-video |
| 2009 | The Revenant | Bart Gregory | Lead Role; Cult Horror-Comedy |
| 2009 | Children of the Corn | Burton Stanton | Syfy TV Movie |
| 2011 | The Maiden and the Princess | Hammond | Short Film |
| 2011 | Archetype | RL7 | Voice Role; Short Film |
| 2012 | Neighbors | Timothy Longshanks | Short Film |
| 2024 | A Christmas in New Hope | Buddy Stevens | Holiday Drama |
STAGE & ADDITIONAL PERFORMANCES:
| Year(s) | Title | Role / Capacity | Notes |
| 1998 | Jesus Christ Superstar | Philip the Apostle | Regional theater; his debut role at age 17 |
| 1999 | Our Town | George | High school production |
| 2000 | My Fair Lady | Freddy Eynsford-Hill | Regional production |
| 2001 | The Diary of Anne Frank | Ensemble | Won the Back Stage West Garland Award for Best Ensemble |
| 2001 | The Source (Ad) | Eminem Double | A print advertisement for The Source magazine |
| 2004 | Alias (Video Game) | Mr. Sark | Voice role; reprised his television character |
| 2005 | Beautiful | Lead / Performer | Off-Broadway rock musical |
| 2006–Present | Band From TV | Lead Vocalist | Charity cover band with other TV stars |
| 2013 | Rockne: The Musical | Knute Rockne | World Premiere; lead role |
| 2021 | Called to Communion | Guest / Host | Ongoing participation in Catholic radio/media |
