We’ve broken the Happy Days Power Rankings into two parts because they’re damn long. You can find part 1 here.
4. Pat Morita (as Matsuo “Arnold” Takahashi) – Morita’s most well known role came right after Happy Days, with 1984’s The Karate Kid, in which he played martial arts mentor Mr. Miyagi. He was nominated for a Best Supporting Actor Oscar and revived the role in three sequels and a short-lived TV show. He was in TV movies Blind Alleys, The Vegas Strip War, Amos, Alice in Wonderland and What Has Four Wheels and Flies. He starred for two seasons in Ohara as a police lieutenant. He provided narration in TV special Big Bird in Japan, marking the second Happy Days actor to have an association with Sesame Street. He was in Honeymoon in Vegas and Even Cowgirls Get the Blues and in episodes of Dave’s World, The French Prince of Bel-Air, Burke’s Law, Murder, She Wrote, Married with Children, Boy Meets World, The Outer Limits, Diagnosis: Murder, and Caroline in the City. He starred in four season Nickelodeon show The Mystery Files of Shelby Woo as Shelby’s grandfather. He was in three episodes of The Hughleys and five of Baywatch and voiced the emperor of China in Mulan and its sequel as well as in Kingdom Hearts. In the 2000s he also appeared in episodes of Yes, Dear and Spongebob Squarepants before dying in 2005. He’s ahead of Bosley for working longer even though he’s only a couple years younger and for getting an Academy Award nomination.
3. Scott Baio (as Chachi Arcola) – After Happy Days, Baio moved right into starring in Charles in Charge, a sitcom which lasted five seasons, half on CBS, and half in first run syndication until 1990. While that show was airing, he was in an episode of Full House, an episode of My Two Dads, a couple of episodes of Out of This World, and TV movies The Truth About Alex and Alice in Wonderland, Baio was in the second season of two season show Baby Talk and starred for two seasons in Dick Van Dyke drama Diagnosis: Murder. He has been in episodes of The Nanny, Veronica’s Closet, Touched by An Angel, and four episodes of Arrested Development as lawyer Bob Loblaw. He also appeared in MTV reality programs Scott Baio is 45…and Single and Scott Baio is 46…and Pregnant. Baio also directed several episodes of The Wayans Bros. and Out of this World as well as 36 episodes of Charles in Charge. He’s ahead of Morita for having the most successful post-Happy Days show.
2. Henry Winkler (as Arthur Fonzanelli) – while to this day Winkler is best known as Fonzie, he’s been busy, particularly in the last decade. He barely acted at all in the second half of the 1980s, apparently only as a voice in TV movies Happily Ever After and Two Daddies? and in an episode of Pryor’s Place. After dipping his toe back in the television water in the early ‘90s with TV movies The Only Way Out and Absolute Strangers and an episode of MacGyver, he starred in short-lived 13 episode series Monty, in which he played a conservative Rush Limbaugh-esque commentator. He finished out the rest of the ‘90s with more TV movies One Christmas (with Katherine Hepburn), A Child is Missing, Dad’s Week Off, and Detention: The Siege at Johnson High, appearances in The Larry Sanders Show, South Park and The Simpsons and roles in films The Waterboy and Scream. He was busier in the first half of the next decade, most notably as incompetent attorney Barry Zuckerkorn in Arrested Development, but also appearing in episodes of King of the Hill, Blue’s Clues, Law & Order: Special Victims Unit, and The Drew Carey Show. He was in three of Third Watch and three of The Practice and in films Down to You, Little Nicky, and Holes. He was a main cast member as one of a family of doctors in the one season Out of Practice and lent his voice to the extremely short-lived and terrible Mitch Hurwitz cartoon Sit Down Shut Up. He was in two episodes of Crossing Jordan, three of Numb3rs, and appeared in Click. Most recently he’s had a recurring role on USA’s Royal Pains as the father of the main two characters and has appeared in Adult Swim’s Childrens Hospital as hospital administrator Sy Mittleman. He’s ahead of Baio for appearing many times more often in the last decade.
1. Ron Howard (as Richie Cunningham) – Well, he got largely out of the acting game after Happy Days, only acting again as his The Andy Griffith Show character in TV special Return to Mayberry and as the narrator for Arrested Development. Ron Howard has been best known for his film directing work, with his big break being 1982’s Nightshift. Afterward, he’s directed Splash, Coccoon, Willow, Parenthood, Backdraft, Far and Away, The Paper, Apollo 13, Ransom, EdTV, How the Grinch Stole Christmas, A Beautiful Mind, The Missing, Cinderella Man, The Da Vinci Code, Frost/Nixon and Angels and Demons (this is a long list I know, and I was going to take out totally unheard of titles, but there really aren’t any). He was nominated for the Best Director Academy Award for Frost/Nixon and won for A Beautiful Mind. He’s also a prominent producer with partner Brian Grazer. He’s executively produced such TV shows as Arrested Development, Sports Night, The PJs, and Felicity as well as his own movies. It’s hard to compare directing to acting, but Howard’s films have been of the commercial and critical level that I think he’s a pretty clear #1.
Television, the Drug of the Nation 
So many Happy Days people in Arrested! I just wish that Mr Miyagi had made an appearance on it.