He has recently starred in the second series of Channel 4's comedy The IT Crowd, he is known in the UK for starring in BBC 2's Roman's Empire, Red Cap and the award-winning docu-drama The Year London Blew Up. He is also well known on Irish television, having starred in the popular RTÉ One drama The Clinic and the drama Showbands alongside Kerry Katona.

O'Dowd has also had roles in a number of films including the 2005 film Festival where he played stand-up comedian Tommy O'Dwyer (a role for which he won a Scottish BAFTA award) and a small role in Vera Drake.

Currently, O'Dowd is continuing in his profession by filming Frequently Asked Questions About Time Travel, a comedy sci-fi film with Marc Wootton, Dean Lennox Kelly and Anna Faris.

Actor:

1. The Boat That Rocked (2009) (filming) .... Simon
2. Hippie Hippie Shake (2008) (post-production) .... Felix Dennis
3. Frequently Asked Questions About Time Travel (2008) (post-production) .... Ray
   
   
4. "The IT Crowd" .... Roy (12 episodes, 2006-2007)
       - Men Without Women (2007) TV episode .... Roy
       - Smoke and Mirrors (2007) TV episode .... Roy
       - Moss and the German (2007) TV episode .... Roy
       - The Dinner Party (2007) TV episode .... Roy
       - Return of the Golden Child (2007) TV episode .... Roy
         (7 more)
5. "Roman's Empire" .... Jase (5 episodes, 2007)
       - Episode #1.6 (2007) TV episode .... Jase
       - Episode #1.5 (2007) TV episode .... Jase
       - Episode #1.4 (2007) TV episode .... Jase
       - Episode #1.3 (2007) TV episode .... Jase
       - Episode #1.1 (2007) TV episode .... Jase
6. Hotel Very Welcome (2007) .... Liam
7. "Doc Martin" .... Jonathan (1 episode, 2006)
       - On the Edge (2006) TV episode .... Jonathan
8. "The Amazing Mrs Pritchard" .... Headmaster (2 episodes, 2006)
       - Episode #1.3 (2006) TV episode .... Headmaster
       - Episode #1.2 (2006) TV episode .... Headmaster
9. Showbands II (2006) (TV) .... Mervin Mooney
   ... aka Showbands 2 (Australia: DVD title)
10. "The Clinic" .... Brendan Davenport (18 episodes, 2003-2005)
        - Episode #3.2 (2005) TV episode .... Brendan Davenport
        - Episode #3.1 (2005) TV episode .... Brendan Davenport
        - Episode #2.8 (2004) TV episode .... Brendan Davenport
        - Episode #2.7 (2004) TV episode .... Brendan Davenport
        - Episode #2.6 (2004) TV episode .... Brendan Davenport
          (13 more)
11. The Year London Blew Up: 1974 (2005) (TV) .... Dowd
12. Festival (2005/I) .... Tommy O'Dwyer
13. Vera Drake (2004) .... Sid's Customer
    ... aka Vera Drake (France)
14. "Red Cap" .... Bernie Maddox (1 episode, 2003)
        - Crush (2003) TV episode .... Bernie Maddox
    

Self:

1. "Never Mind the Buzzcocks" .... Himself (1 episode, 2008)
       - Episode #21.11 (2008) TV episode .... Himself
2. "8 Out of 10 Cats" .... Himself (1 episode, 2006)
       - Episode #2.4 (2006) TV episode .... Himself
3. Brit Awards 2006 (2006) (TV) .... Himself - Presenter
4. 3rd Irish Film and Television Awards (2005) (TV) .... Himself
   

Archive Footage:

1. "Never Mind the Buzzcocks"
       - Never Mind the Buzzcocks: A Moving Tribute (2008) TV episode .... Himself