Daniel Fitzgerald "Danny" Reagan is a fictional NYPD Detective First Grade, and one of the main characters in the television series Blue Bloods.

[7] They lived at 1712 Amboy Road on Staten Island until a drug cartel retaliated against a recent bust that Danny had made by firebombing their home in the season 7 finale "The Thin Blue Line".

During high school, Danny dated Marianne Romano (Charisma Carpenter), who was described by his partner Baez as "the queen bee, super good looking, a little crazy, and dynamite in the sack" to which he agreed.

[9] In several episodes in the earlier seasons, it is clearly established in dialogue that Danny was the oldest of the siblings followed by Erin, Joe and Jamie[10] in that order; Frank mentions that Danny was in diapers during the Watergate hearings which took place in 1973-74, while the final scene at the Reagan family plot in the episode "The Blue Templar" shows Joe's date of birth on his headstone as June 6, 1977.

[11] For a class project of Nicky's, Danny mentioned that when he was three years old, he wanted to be a firefighter for Halloween, but his grandfather Henry swore that as long as he was alive, no Reagan would ever be a member of the FDNY, got him into a police uniform, and he "never took it off" until he made Detective.

[12] On the job since autumn 1995,[13] Danny took a leave of absence from the New York City Police Department to serve two tours in the Iraq War as a Marine.