Television:
* The Wire (2002-2008): He played Detective Thomas "Herc" Hauk, a recurring character throughout the series.
* Oz (1997-2003): He had a recurring role as Officer Michael "Mick" O'Regan.
* Law & Order: Special Victims Unit (1999-present): He appeared in multiple episodes as different characters.
* The Shield (2002-2008): He guest-starred in several episodes as a different character each time.
* Third Watch (1999-2005): He played Officer Carl "Cowboy" Roberts.
* Blue Bloods (2010-present): He has had a recurring role as Detective Sean Reagan, a brother to the main character, Danny Reagan.
* Elementary (2012-2019): He appeared in several episodes as the character, "Lestrade."
* The Good Wife (2009-2016): He guest-starred in one episode as a politician.
* Madam Secretary (2014-2019): He appeared in several episodes as the character, "Paul."
Film:
* The Wolf of Wall Street (2013): He played the role of "Donny."
* The Taking of Pelham 1 2 3 (2009): He played the role of "Detective Garcia."
* The Departed (2006): He played the role of "Sergeant Barrigan."
* The Interpreter (2005): He played the role of "Captain Johnson."
* The Clearing (2004): He played the role of "Father."
* The Majestic (2001): He played the role of "The Sheriff."
This is just a sample of his extensive filmography. He has also had roles in several other television shows and films, both big and small.
If you are interested in a more complete list, you can search for "Mark Moraghan" on websites like IMDb or The Movie Database.