Henry Allen was created by John Broome and Carmine Infantino in The Flash #126.
Henry Allen was a doctor in Fallville, Iowa while being married to Nora Allen. Their son was Barry Allen who eventually went on to become the Flash.
The Flash: Rebirth
In The Flash: Rebirth, Barry Allen's back story becomes ret-conned. When Barry was a kid, Nora was murdered and Henry was convicted of the crime. Barry still believed his father was innocent, driving him to become a policeman, in hope of finding the real killer and proving his father's innocence.
The Flash (1990)
Henry Allen appeared in the 1990's Flash TV show. He is portrayed as having worked as a beat cop for 30 years before retiring. He also inspired his sons Barry and Jay Allen to join the police force. He doesn't appreciate Barry's crime lab work as he does Jay's work on the streets. He is portrayed by actor M. Emmet Walsh.
The Flash (2014)
Henry Allen appears in the CW Arrow spin-off The Flash portrayed by John Wesley Shipp, who in turn played Barry Allen in the original 90's television series. Like his modern comic counterpart, Henry is falsely imprisoned in Iron Heights for the death of his wife when Barry was a child, a crime actually committed by the Reverse Flash. Throughout the first season, Barry works with Detective Joe West to try and find evidence to exonerate his dad.
The Flash (2018)
Billy Crudup will be portraying Henry Allen in The Justice League movie in 2018.