Danny "Danno" Williams is a fictional character from CBS' Hawaii Five-O, and is the partner of Five-0 leader, Steve McGarrett. Williams was portrayed by James MacArthur in the original show from 1968 to 1979, and later by Scott Caan in the series' remake from 2010 to 2020.
Hawaii Five-O (1968–1980)
In the original show, Danny Williams was portrayed by James MacArthur from 1968 to 1979. In the series premiere, "Cocoon", Danny was played by Tim O'Kelly. MacArthur played the role for the rest of the first eleven seasons, appearing in 268 episodes. The only episode of the first eleven seasons, other than "Cocoon", that MacArthur did not appear in, was "Once Upon a Time: Part 2". In season twelve, the character was replaced by a new character, James Carew, who was portrayed by William Smith. MacArthur returned to reprise the role of Danny, who had become Hawaii's governor in the plot, in the 1997 unaired pilot of Hawaii Five-O.
In "Retire in Sunny Hawaii...Forever", it is revealed that Danny has an aunt named Clara (portrayed by MacArthur's mother, Helen Hayes). In "The Clock Struck Twelve", it is revealed that Danny is skilled at defusing bombs.
MacArthur had agreed to guest-star in an episode of the first season of the reboot, but he died on October 28, 2010, before filming his appearance.
Hawaii Five-0 (2010–2020)
In the reboot, Danny Williams is portrayed by Scott Caan from 2010 to 2020. Caan portrayed Danny in all ten seasons, appearing in 208 episodes. Caan also portrayed Danny in a crossover episode with NCIS: Los Angeles. Scott Caan was nominated for the Golden Globe Award for Best Supporting Actor – Series, Miniseries or Television Film, in 2011, and for the Teen Choice Award for Choice Action TV Actor, in 2013, for his portrayal of Danny. Caan, along with Alex O'Loughlin, won the TV Guide Award for Favorite Bromance, in 2013, for their portrayal's of Danny and Steve McGarrett, respectively.
Detective Sergeant Daniel "Danny" "Danno" James Williams is a member of the Five-0 Task Force and the de facto second in command. He is an experienced detective whose police background and tendency to go "by the book" clashes with McGarrett's "shoot now, talk later" style.
It is established in Season 1 that Danny was from New Jersey, presumably around the New York metropolitan area, and was only living in Hawaii because his ex-wife Rachel had remarried and moved there with their daughter Grace to join her new husband Stan Edwards. He transferred from Newark PD to the Honolulu PD to be closer to Grace. In the Pilot, Danny had moved to Hawaii six months ago and was a "greener than grass" homicide detective with the HPD when he was assigned the murder investigation of John McGarrett. He comes into contact with John's son Lieutenant Commander Steve McGarrett, then still on active duty, who returns home to Hawaii seeking revenge and intending to take over the investigation into the murder of his father. The Governor had requested the younger McGarrett to set up a task force and Danny was his first recruit. They then recruit Chin Ho Kelly and Kono Kalakaua to form the Five-0 Task Force.
Danny often rants to McGarrett about his dislike for everything Hawaiian, from pineapples on pizza to surfing etiquette, while McGarrett would mock his affinity for wearing ties and loafers at work, a practice not common in Hawaii. Regarded as a haole for being a non-Hawaiian and not following island customs during the first season, Danny is often viewed as a curiosity or with disdain by the locals and other HPD cops and the first season sees the rest of the team often having to explain to him the idiosyncrasies of life in Hawaii. For example, his insistence on wearing what he deemed to be "professional attire" (tie and loafers) and disregard for surf etiquette or Native Hawaiian culture is met with ridicule and light-hearted derision from his co-workers. He eventually stops wearing ties and, in the season 5 premiere, admits that he feels at home in Hawaii and views his Five-0 co-workers as his extended family.