Ed note: we're having a few technical difficulties here, so we're highlighting a few best-of posts starting with this terrific one from Kara. Enjoy!

Things don't always work out as planned in Television Land. A snappy catchphrase, an adorable mannerism, a bodacious bust line"¦there's no telling what might capture the audience's attention. The problem is, it often comes at the expense of another actor.

1. The Fonz Upstages Opie

The idea for a sitcom set in the 1950s was inspired by a vignette on the 1970s anthology series Love, American Style. One year after "Love and the Happy Days" aired, Ron Howard starred in the blockbuster film American Graffiti, which solidified his ability to play a retro-teenager. Howard had previously played "Opie" on The Andy Griffith Show, and with his recent film triumph under his belt, it was clear that he was the intended star of Happy Days. But the producers were caught by surprise when Fonzie, portrayed by Henry Winkler, who was only an occasional character during the first season started getting a substantial amount of press. Suddenly "Ayyyy" was on everyone's lips and you couldn't walk past a storefront without seeing some sort of Fonz replica giving the ol' thumbs up. The ABC brass even suggested changing the name of the show to Fonzie's Happy Days, but Henry Winkler himself vehemently opposed such a change. In fact, Henry has always staunchly credited the success of Happy Days to the work of entire cast, particularly Ron Howard and Tom Bosley.

2. Alex P. Keaton's Hostile Takeover

When Gary David Goldberg was casting Family Ties, a sitcom about liberal 60s-era parents raising 80s-era children, he envisioned Matthew Broderick for the role of Alex P. Keaton. But Broderick didn't want to leave New York for a long-term project, so Goldberg was left at square one. At the urging of a casting director, he gave a young Canadian actor named Michael J. Fox a second screen test, and reluctantly hired him (his infamous comment at the time about Fox was "There's a face you'll never see on a lunch box.") Much to everyone's surprise, Michael J. Fox had that on-screen charisma that quickly made him an audience favorite; he could deliver the most extreme right-wing political rhetoric and make it palatable because he was so darned cute. Meredith Baxter-Birney was miffed, because her understanding when she signed on for Family Ties was that the parents would be the focus of the series. But teen magazine profiles and posters can have a unique impact on a celebrity's "Q-factor," and soon many of the show's plots revolved around Alex. During the taping of the episode where Alex lost his virginity, the audience's laughter went on so long that the show ran 12 minutes overtime. Goldberg was standing backstage with Baxter-Birney at the time and commented, "If you want to leave the show, I'll understand."

3. Jack Tripper Gets Bested by a Blonde

When Three's Company was being cast, John Ritter was the only actor hired who any sort of name recognition, having played the Reverend Fordwick on The Waltons. Luckily, he also had a knack for slapstick comedy, and managed to make the most out of what was basically a one-joke role (a closet heterosexual living platonically with two beautiful young women). But even though Ritter was the acknowledged star of the show (and won an Emmy Award for his portrayal of Jack Tripper), it was Suzanne Somers who got her picture on all the magazine covers and had her own mega-selling poster. Actually, as soon as Somers landed the role of Chrissy, she contacted powerhouse manager Jay Bernstein and begged him to take her on as a client. She wanted to be "bigger than Farrah," and although (according to Somers) Bernstein questioned her looks and her talent, he was impressed by her passion, and agreed to manage her. Of course, it probably helped that Somers also pledged to give him every penny of her salary from the first six episodes of Three's Company. Nevertheless, thanks to Bernstein's savvy promotion, soon every episode of Three's Company, no matter what the plot, focused heavily on Chrissy prancing around in tight T-shirts and short-shorts.

4. Yes, Urkel Did That

Family Matters was officially a spin-off of Perfect Strangers (Harriette Winslow was the elevator operator at the Chicago Chronicle). The show was supposed to focus on the everyday trials and tribulations of a department store employee, her police officer husband, and their three children. Midway through Season One, their nerdy neighbor Steve Urkel (portrayed by Jaleel White) appeared, oversized glasses, suspenders, high-rise pants, squeaky voice and all. Urkel was originally intended as a one-episode character, but after White's initial appearance, studio audiences started chanting "Urkel! Urkel!" during subsequent tapings. Several first-season episodes were hastily re-written in order to feature the whiny-voiced, clumsy character. Interestingly enough, Jaleel White had been acting (mostly in commercials) since the age of three, and just prior to being cast as Urkel had told his mother that he wanted to quit the business in order to play JV basketball when he entered high school the next fall.

5. Mr. Kotter's Lukewarm Welcome (in comparison to John Travolta)

Veteran comic writer Alan Sacks had seen stand-up comic Gabe Kaplan's act a few times and thought that there might be a viable sitcom to be mined out of Kaplan's tales of his days in remedial high school classes. When previewing Welcome Back, Kotter in front of test audiences, network brass noted that John Travolta (whose character was then known as "Eddie Barbarina") elicited unsolicited random squeals from the crowd and decided on the strength of a possible teen heartthrob plus Kaplan's jokes to green light the series. Travolta, for his part, didn't discourage the Tiger Beat aspect of his fame, but he also craved acceptance as a bona fide actor, and he spent much of his Kotter salary on a high-priced agent, who landed him progressively larger film roles, from The Boy in the Plastic Bubble, to Carrie, to Saturday Night Fever. By the fourth (and ultimately final) season of Welcome Back, Kotter, John Travolta was billed as a "special guest star" and appeared in less than half of that season's episodes.