Movies:
* The Divide (2011)
* The Day the Earth Stood Still (2008)
* The Jacket (2005)
* The Sum of All Fears (2002)
* Best Laid Plans (1999)
* The Postman (1997)
* The Fan (1996)
* The Last Supper (1995)
Television:
* The Good Fight (2017-present) - recurring role as Julius Cain
* Elementary (2012-2019) - recurring role as Captain Gregson
* Lie to Me (2009-2011) - recurring role as Agent Ben Reynolds
* The Shield (2002-2008) - recurring role as Detective Kevin Hiatt
* ER (1994-2009) - recurring role as Dr. Mark Greene
* The Practice (1997-2004) - recurring role as Alan Birch
* Homicide: Life on the Street (1993-1999) - recurring role as Detective Ray Cole
* NYPD Blue (1993-2005) - recurring role as Detective Mike "The Duke" Deakins
Other:
* The Wire (2002-2008) - voice role as Detective Roland 'Prez' Pryzbylewski
This is not an exhaustive list, but it gives you a good overview of Reed Diamond's career in film and television. He has played a wide range of characters, from cops and doctors to government agents and powerful lawyers, and he is known for his ability to bring depth and realism to his roles.