William Zabka

Zabka was born in New York City, the son of Nancy, a business liaison, producer, and production assistant, and Stan Zabka, a director, writer, and composer. Zabka has a brother and a sister. Stan is of Czech descent and was born in Des Moines, Iowa. He worked as production manager on many motion pictures, including the Chuck Norris film Forced Vengeance (1982).

In 1983, Zabka graduated from El Camino Real Charter High School in Los Angeles, California, before briefly attending California State University, Northridge and majoring in film.Zabka's breakout acting role came in his first movie, The Karate Kid (1984). Zabka played Johnny Lawrence, the main antagonist to the title character and protagonist played by Ralph Macchio. At the time, Zabka had no training in karate, but was an accomplished wrestler. Participating in the film inspired Zabka to learn the martial art of Tang Soo Do and he later earned a second–degree green belt.

Later in the 1980s, Zabka appeared in the comedy movies Just One of the Guys (1985) and Back to School (1986). He co-starred on the CBS television series The Equalizer as the son of the title character (1986–89). Zabka also played Jack, Audrey's jock boyfriend, in National Lampoon's European Vacation (1985). Zabka later tried to step away from playing the class bully character. In an interview, Zabka mentioned that he was sometimes hassled in public by random people due to the villainous characters he was best known for.

During the 1990s and 2000s, Zabka acted mostly in independent films while studying to be a filmmaker. In 2003, he wrote and produced the short film Most (aka The Bridge) shot on location in the Czech Republic and Poland. Most had its world premiere at the Sundance Film Festival in 2003 and won numerous awards at prestigious film festivals, including Best of Festival at the Palm Springs International Festival of Short Films in 2003. In 2004, Zabka was nominated for an Academy Award for Most in the Live Action Short Film category.

In 2007, Zabka directed and starred in a music video for the band No More Kings' song, "Sweep the Leg." The video stars Zabka as a caricature of himself, living in a trailer in the desert and obsessed with his role in The Karate Kid. The video includes cameos by several of the original Karate Kid cast members, including Martin Kove and Ralph Macchio.

In 2010, Zabka directed Rascal Flatts in their music video for the song "Why Wait" and also directed the video for their 2017 hit "Yours If You Want It." That same year, Zabka made a cameo appearance in the comedy movie Hot Tub Time Machine.

In 2013, Zabka and Macchio guest starred in the season 8 episode of How I Met Your Mother, "The Bro Mitzvah." Zabka also appeared in several episodes of the sitcom's ninth season, playing a fictional version of himself. Zabka also directed commercials for clients including Little Tikes and Verizon at Heresy in Venice, California.

On August 4, 2017, it was announced that Zabka would reprise his role as Johnny Lawrence in a 10-episode Karate Kid revival series for YouTube Red titled Cobra Kai that debuted in 2018. Zabka also co-executive produces the series with Ralph Macchio. The series begins 33 years after the events of the first film, and revolves around a down and out Johnny who, seeking to rebuild his life, reopens the Cobra Kai dojo. It reignites his rivalry with a now successful Daniel LaRusso (Macchio), who has been struggling to maintain balance in his life without the guidance of his now deceased mentor, Mr. Miyagi.