Title: Steve McGarrett
Content:  Steve McGarrett is a fictional character who is the protagonist of CBS' Hawaii Five-O. McGarrett is a former United States Navy officer and the leader of a special state police task force, which is called Five-O. McGarrett was portrayed by actor Jack Lord in the original show from 1968 to 1980, and later by Alex O'Loughlin in the series' remake from 2010. Throughout the show, McGarrett is partner to Detective Danny "Danno" Williams.
Title: Hawaii Five-0 (2010 TV series)
Content:  In February 2010, it was announced that Daniel Dae Kim had been cast to play Chin Ho Kelly, an ex-cop trained by Steve McGarrett's father. He was the first actor cast for the remake. Several days later, Alex O'Loughlin was cast as Steve McGarrett, the son of ex-cop John McGarrett (portrayed by William Sadler). The producers pay homage to the original series throughout the first year by making one of Steve's hobbies restoring his father's 1974 Mercury Marquis, which is in fact the actual car driven by Jack Lord in the latter half of the original series' run. Actress Grace 
Title: Hawaii Five-0 (2010 TV series, season 5)
Content: Alex O'Loughlin as Lieutenant Commander Steven "Steve" McGarrett, United States Navy Reserve ; Scott Caan as Detective Sergeant Daniel "Danno" Williams, Honolulu Police Department ; Daniel Dae Kim as Detective Lieutenant Chin Ho Kelly, Honolulu Police Department ; Grace Park as Officer Kono Kalakaua, Honolulu Police Department ; Masi Oka as Dr. Max Bergman, Chief Medical Examiner ; Chi McBride as Captain Lou Grover, Honolulu Police Department ; Jorge Garcia as Jerry Ortega 
Title: Steve McGarrett
Content:  In the original show, Steve McGarrett was portrayed by Jack Lord from 1968 to 1980. McGarrett was a former United States Navy Lieutenant and Detective Captain in the Honolulu Police Department who had been requested by Governor Paul Jameson to head the Five-O Task Force, a fictional equivalent of the FBI intelligence police. He was portrayed as a highly driven cop and workaholic, often staying at his office until midnight. It was said that he "only takes orders from the Governor and God – and occasionally even they have trouble". McGarrett had a sister Mary Ann (Nancy Malone). Their mother was murdered by criminals when 
Title: List of Hawaii Five-0 (2010 TV series) characters
Content: Portrayed by Terry O'Quinn  Lieutenant Commander Joe White, USN (Ret.) (born July 9, 1954 ) was Steve McGarrett's former SEAL trainer and a long-time friend of John McGarrett and mentor to Steve. A Wisconsin native, he is a "mustang", having been a master chief petty officer before gaining a commission and retiring as a lieutenant commander. He appears to be well known amongst SEALs from his time as a trainer at the Naval Special Warfare Center, as McGarrett's former SEAL teammate Billy Harrington and SO2 Graham Wilson, who was a person of interest in the episode "Hoʻapono", both knew of 
Title: Honolulu Police Department
Content:  The most famous Hawaii based crime drama was Hawaii Five-O which aired on the CBS television network from September 1968 to April 1980. Until Law & Order, Hawaii Five-O was the longest running crime series on American television. Jack Lord starred as Steve McGarrett, head of the elite state law enforcement office which worked alongside the chief of the Honolulu Police Department. James MacArthur starred as Danny Williams, McGarrett's right-hand man. McGarrett and "Danno" were straight-laced men with extreme dedication to law and justice fighting the forces of evil around the islands, especially in seedy downtown dives. Kam Fong Chun (who played 
Title: Alex O'Loughlin
Content:  Alex O'Loughlin (born 24 August 1976) is an Australian actor, writer, director, and producer, who played Lieutenant Commander Steve McGarrett on CBS' remake of the TV series Hawaii Five-0 (2010–2020). He had starring roles in the films Oyster Farmer (2004) and The Back-up Plan (2010), as well as on such television series as Moonlight (2007-2008) and Three Rivers (2009-2010).
Title: Hawaii Five-0 (2010 TV series, season 6)
Content: Alex O'Loughlin as Lieutenant Commander Steven "Steve" McGarrett, United States Navy Reserve Five-O Task Force ; Scott Caan as Detective Sergeant Daniel "Danny" "Danno" Williams, Honolulu Police Department, Five-O Task Force ; Daniel Dae Kim as Detective Lieutenant Chin Ho Kelly, Honolulu Police Department, Five-O Task Force ; Grace Park as Officer Kono Kalakaua, Honolulu Police Department, Five-O Task Force ; Masi Oka as Dr. Max Bergman, Chief Medical Examiner ; Chi McBride as Captain Lou Grover, Honolulu Police Department, Five-O Task Force ; Jorge Garcia as Jerry Ortega, Special Consultant, Five-O Task Force 
Title: Hawaii Five-0 (2010 TV series, season 9)
Content: Alex O'Loughlin as Lieutenant Commander Steven "Steve" McGarrett, United States Navy Reserve ; Scott Caan as Detective Sergeant Daniel "Danny" "Danno" Williams ; Ian Anthony Dale as Officer Adam Noshimuri ; Meaghan Rath as Officer Tani Rey ; Jorge Garcia as Special Consultant Jerry Ortega ; Beulah Koale as Officer Junior Reigns ; Taylor Wily as Kamekona Tupuola ; Dennis Chun as Sergeant Duke Lukela, Honolulu Police Department ; Kimee Balmilero as Dr. Noelani Cunha, Medical Examiner ; Chi McBride as Captain Lou Grover 
Title: Hawaii Five-0 (2010 TV series, season 7)
Content: Alex O'Loughlin as Lieutenant Commander Steven "Steve" McGarrett, United States Navy Reserve ; Scott Caan as Detective Daniel "Danny" "Danno" Williams, Honolulu Police Department ; Daniel Dae Kim as Lieutenant Chin Ho Kelly, Honolulu Police Department ; Grace Park as Officer Kono Kalakaua, Honolulu Police Department ; Masi Oka as Dr. Max Bergman, Chief Medical Examiner (episodes 1–13) ; Chi McBride as Captain Lou Grover, Honolulu Police Department ; Jorge Garcia as Jerry Ortega 

Question: who played the original steve mcgarrett on hawaii five-o?
Answer: John Joseph Patrick Ryan.
Jack Lord.