who plays erin reagan's husband on blue bloods
Peter Hermann (actor) He also guested on 30 Rock during its first season, and starred in ABC's mid-season replacement series, Cashmere Mafia, as Davis Draper. As of 2011 he appears in the Broadway play War Horse, and makes occasional appearances as Erin Reagan's ex-husband John "Jack" Boyle on Blue Bloods.[6][7][8]