Beau van den Ecker served as stunt man on Hawaii Five-O, as well as director and associate producer in the later seasons. Here are his Five-0 appearances as an actor:
“Strangers in Our Own Land” (uncredited, maybe) I think that’s him running own at the beginning with the fire extinguisher. Hard to tell with those sunglasses the guy is wearing.
“Twenty-four Karat Kill” (uncredited) He’s the guy who jumps off the boat to tie a rope around the sacks of illegal gold.
“And They Painted Daisies on His Coffin” (uncredited) Appears on the beach with Tommy Tommy and others. Gets flipped by McGarrett.
“To Hell With Babe Ruth” (Security Guard) Killed in the teaser, throat cut by a Ninja’s throwing star. First episode where Beau is in the end credits.
“Savage Sunday” (Security Guard) Seriously wounded in the teaser by the invading mercenaries.
“A Bullet For McGarrett” (uncredited) Drives the truck that hits and kills the hypnotized girl.
“Run, Johnny, Run” (Fred Waters) Plays a SP sailor, killed in the teaser while attempting to arrest John Mala. First episode where Beau has some dialogue. It's also clear in this episode how short Beau is ... or how tall Christopher Walken is. Side by side Beau looks a foot shorter.
“Ten Thousand Diamonds and a Heart” (uncredited) He’s one of the men killed in the teaser. Beau does a great job with his gunshot recoil complete with sunglasses flying off.
“The Gunrunner” (First Separatist) Appears at the end of act three; shot down during the raid on the weapons at the airport. “Onscreen for fifteen seconds”, Mr. Mike.
“And I Want Some Candy, and a Gun That Shoots” (Officer Ryder) The first cop killed by the psychotic sniper. “Though his face is barely seen, he rates a credit at the end”, Mr. Mike.
“V for Vashon, The Patriarch” (Chuck Price) Plays an HPD officer small and agile enough to recreate how someone could have snuck down into the elevator. Is in only one scene, but with some lines.
“The Clock Struck Twelve” (Ellsworth) An HPD man, McGarrett has him create a diversion to the nighttime security at the threatened courthouse (security McGarrett set up). Beau does this by crashing a car, then laughing his head off.
“Hookman” (uncredited) Is seen driving the hearse at the beginning. He loses control of the hearse which causes the coffin to come sliding out the back (brilliant!).
“Bomb, Bomb, Who’s Got the Bomb?” (uncredited) Is behind the wheel of a car that speeds off from the opening explosion at the senator’s house. He’s killed at the end of the first act, behind the wheel of a car that goes off the road in a fiery explosion. Beau’s character is named Nick Landis.
“Diary of a Gun” (Frito) Probably his largest role. He plays a punk who gets his hands on a gun that’s been involved in several shootings. He quickly adds more shootings to the gun’s list, going on a brazen crime spree. Beau probably has him most dialogue here, and is seen in much of the last act.
“6,000 Deadly Tickets” (uncredited) Plays a lame security guard, shot dead for the 6,000 deadly tickets.
“The Case Against McGarrett” (uncredited) Plays a prisoner who’s umpire in a prison yard ballgame. He starts a ruckus by belting a player who objects to his (terrible) call.
“Loose Ends Get Hit” (uncredited) He’s one of Jimmy Borges’s goons. I think his name is Dewey.
"The Capsule Kidnapping" A brief appearance as a diver at the end. He also plays a HPD officer when Steve and Danno go to the apartment of Paul Colburn about midway through this episode. When Colburn shows up, Steve yells to the cop to stop him. Rumoured that this cop is Beau, in disguise, who gets to chase after Colburn (Bruce Boxleitner) (thanks to Fred Helfing).
“Nine Dragons” (uncredited) Attacks McGarrett just as he’s entering the Hong Kong police department. He’s dressed up as one of the Nine Dragons gang members, complete with phony mustache and hat, but is recognizable just from his “karate yell”.
“Double Exposure” (Sammy Nolo) The second of the two crime figures killed by a couple of usurpers in the Doyle Weston camp. Beau is hit by a car and thrown onto the hood, shattering the windshield. He’s taken on a brief, wild, hood-top ride before being dumped over a wall into the water.
“Elegy in a Rain Forest” (Homer Wamono) An associate of a rapist-murderer recently escaped from custody, he’s pursued by Chin and Duke. He’s taken in after a martial arts exchange with Duke. No dialogue except for that “AHHHHHH” karate yell.
“You Don’t See Too Many Pirates These Days” (Joey) Plays a ship worker who tries to escape when the ship is taken over by “pirates”. He is gunned down attempting to swim to shore.
“A Short Walk on the Longshore” (The Knife) With another, attempts to jump the in-disguised McGarrett. Takes a good beating for his trouble.
“Head to Head” (Harry Sunday) A nasty hitman who comes to Hawaii to eliminate a two-faced witness. Has quite a few scenes here.
“Death Mask” (1st man) In the opening, he gets into a scuffle with Chuck Couch. The scuffle is a diversion while some young hothead attempts to steal the famous Death Mask. It’s funny how Beau and Couch are two of Five-0’s stuntmen yet their scuffle looks like two old men wrestling over checkers.
“Stringer” (uncredited) An HPD man who’s with Duke in a car tailing Tony Alika. The car is shot off the road and Beau is burned to death in the crash.
I don’t believe Beau made any appearances in the twelve season. With him being Associate Producer and sometime director (e.g. “The Golden Noose”), he was probably too busy to get blown up, gunned down, or judo-flipped. Too bad -- the series was definitely better when he was doing those things.