Donald Sage MacKay was an actor best known for his portrayal of characters throughout various television series. MacKay started his acting career landing roles in dramatic series like "ER" (NBC, 1994-2009), "JAG" (CBS, 1995-2005) and "7th Heaven" (1996-2007). He also appeared in "The Practice" (ABC, 1997-2004) and "Providence" (NBC, 1999-2002). MacKay also provided his talents as a voice actor for the Michelle Nicastro animated sequel "The Swan Princess: Escape from Castle Mountain" (1997). Several more television roles followed in the early 2000s, including stints on "The District" (2000-04), "Scrubs" (2001-2010) and "NCIS" (CBS, 2003-). He also appeared in "Criminal Minds" (CBS, 2005-). More recently, he tackled roles on "House" (2004-2012), "Mad Men" (AMC, 2007-2015) and "Modern Family" (ABC, 2009-). He also appeared in "Blue Bloods" (CBS, 2010-) and "Elementary" (CBS, 2012-). Most recently, MacKay acted on "Masters of Sex" (Showtime, 2013-16).