1 of 12 CBS/Landov
The ruggedly handsome actor played Steve McGarrett, the head of Five-O, as a no-nonsense guy — the one who culminated cases with the famous phrase, "Book 'em, Danno." He died in 1998.
2 of 12 Gareth Cattermole/Getty Images
It's up to him to fill Lord's shoes. And CBS apparently believes in a three-strike rule when it comes to him, having canceled his previous two series, Moonlight and Three Rivers.
3 of 12 CBS/Landov
Danny Williams, the detective who was the "Danno" in "Book 'em, Danno." Fun fact that probably few people knew, then or now: He's the (adopted) son of the so-called First Lady of the Theater, Helen Hayes, and playwright Charles MacArthur.
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The new "Danno" is also the son of a famous performer — James Caan, forever memorable as Sonny in The Godfather. In the pilot, the actor, whose credits include Entourage and the Ocean's Eleven trilogy, is the most compelling and fully developed character — even more so than O'Loughlin's McGarrett.
5 of 12 CBS/Landov
The actor who played Chin Ho actually was a Honolulu police officer from 1946 to 1962. And he ran for governor in 1989. He died in 2002.
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Daniel Dae Kim
From one island to another. The Lost actor takes the role of the new Chin Ho — an unfairly discredited cop who gets another chance with Five-O.
7 of 12 CBS/Landov
"Zulu as Kono" may be the easiest-to-remember opening credit of a TV show ever — certainly better than "Gilbert Francis Lani Damian Kauhi (the actor's real name) as anybody." Good thing he earned the nickname Zulu in high school.
8 of 12 Jesse Grant/WireImage.com
Now it's "Park as Zulu" in a gender change to the character. The Battlestar Galactica actress fills the role of Kono's cousin, who's a surfer-dudette eager to show her skill set while barely out of the police academy.
9 of 12 Everett Collection
The stolid character actor played Gov. Paul Jameson. Five-0 specifically was an elite branch of the Hawaii State Police headed by McGarrett (Jack Lord) and answerable only to the governor. He died in 1998.
10 of 12 Jason Merritt/FilmMagic.com
Another gender change to a role in the new series: The Emmy winner, whose TV credits include Designing Women, Frasier, Samantha Who? and 24, is Gov. Pat Jameson in the reboot, so she's the boss.
11 of 12 Everett Collection
He played one of the best recurring prime-time TV villains of the time — and with a great name, too: Wo Fat. Although the veteran actor — who appeared as the brainwasher in 1962's The Manchurian Candidate — portrayed innumerable Asians during his career, he was actually of Anglo-Egyptian-Sudanese ancestry. He died in 1991.
12 of 12 Jean Baptiste Lacroix/WireImage.com
The Sons of Anarchy alum plays Mary Anne, the sister of O'Loughlin's McGarrett (although she does not appear in the pilot). Lord's McGarrett also had a sister, whom many fans may forget. (A two-parter in Season 1 dealt with the loss of her baby.)