Casting
As the "Miyagi-verse" that shapes Cobra Kai consists of characters who interacted with Mr. Miyagi, the series offers a deeper exploration of themes and characters from The Karate Kid (1984), The Karate Kid Part II (1986), and The Karate Kid Part III (1989). All of the main actors, and a few supporting actors, reprise their original roles. With regard to The Karate Kid animated children's show (1989), Hurwitz has stated that he doesn't consider it to be part of the Miyagi-verse canon, but an Easter egg from it appears in season three, in response to the question about its status within Cobra Kai.
In addition, throughout Cobra Kai's run, there was speculation that Hilary Swank might reprise the role of Julie Pierce from The Next Karate Kid (1994). According to Heald, they had a storyline involving Julie related to Mr. Miyagi and the mystery of a stolen necklace, "but before we got too deep, we had to reach out to Hilary and find out would she be willing to come and play with us." At the end of the series in 2025, Heald, Hurwitz, and Scholssberg stated that Swank would not appear as, "people have all sorts of reasons why they will or will not be participating in something, and with the timing of whatever was going on, it just was never an option." However, they also indicated that they will "have to see what might happen in this universe if we're fortunate enough to continue writing within it. She's a character that we have a lot of excitement to revisit."
In season one, Macchio and Zabka reprised their respective roles of Daniel LaRusso and Johnny. Additional The Karate Kid actors included Randee Heller as Daniel's mother Lucille LaRusso, and Martin Kove as John Kreese. The cast list for season one included Xolo Maridueña as Miguel Diaz, Mary Mouser as Daniel's daughter Samantha "Sam" LaRusso, Tanner Buchanan as Johnny's son Robby Keene, and Courtney Henggeler as Daniel's wife Amanda. Ed Asner was cast in a guest role as Johnny's wealthy, verbally abusive step-father, Sid Weinberg. Vanessa Rubio joined the cast as Miguel's mother Carmen.
In season two, Macchio, Zabka, Maridueña, Mouser, Buchanan, and Henggeler all returned, with Jacob Bertrand, Gianni DeCenzo, and Kove being promoted to series regulars, and newcomers Paul Walter Hauser and Peyton List joining the cast. The Karate Kid actors Heller, Rob Garrison (Tommy), Ron Thomas (Bobby), and Tony O'Dell (Jimmy) made guest appearances during this season.
In season three, Macchio, Zabka, Maridueña, Mouser, Buchanan, Henggeler, Bertrand, DeCenzo, and Kove returned. Reprising their roles from The Karate Kid and The Karate Kid II in guest appearances during this season were Elisabeth Shue (Ali Mills), Ron Thomas (Bobby), Tamlyn Tomita (Kumiko), Traci Toguchi (Yuna), and Yuji Okumoto (Chozen Toguchi).
In season four, Rubio and List were promoted to series regulars, while Dallas Dupree Young and Oona O'Brien were cast in recurring roles. In addition, Thomas Ian Griffith reprised his role as Terry Silver from The Karate Kid Part III, while Okumoto and Heller made guest appearances.
In season five, Okumoto had a recurring role as Chozen. In addition, Sean Kanan and Robyn Lively reprised their respective roles as Mike Barnes and Jessica Andrews from Part III. Alicia Hannah-Kim also joined the cast as Kim Da-eun while Young was upgraded to a series regular.
In season six, Kanan returned as Barnes, Griffith returned as Silver, William Christopher Ford reprised his role as Dennis de Guzman from Part III, and Darryl Vidal reprised his role from The Karate Kid. C. S. Lee was cast to portray Master Kim Sun-Yung, a character first referenced by Terry Silver in that film. Lewis Tan, Patrick Luwis, and Rayna Vallandingham joined the cast in supporting roles.
