It had Efrem Zimbalist Jr. as Zorro's father Don Alejandro de la Vega in season one
Replaced in the rest of the series by Henry Darrow, who was the first Latino actor to play Zorro/Don Diego, in the 1980 Filmation animated series and three years later in the very short-lived sitcom bomb
Zorro and Son.
That makes Darrow one of the few people to appear in three different Zorro productions. I'm only aware of two others. George J. Lewis played supporting roles in the Republic Serials
Zorro's Black Whip (which had nothing to do with Zorro besides the title, being about a female Zorro-like character in the American Old West) and
Ghost of Zorro (with a pre-Lone Ranger Clayton Moore as Zorro's grandson) before he went on to play Don Alejandro in the 1950s Disney series. And Don Diamond, Corporal Reyes in the '50s series, voiced Sgt. Gonzales in the '80 animated series and had a bit part in a
Zorro and Son episode.
I can think of a few others who appeared in two different Zorro incarnations: Noah Beery was the villain in the 1920 silent movie
The Mark of Zorro and the first Republic serial
Zorro Rides Again, and the 1974 TV movie remake of the 1940
The Mark of Zorro featured two guest villains from the 1960-61 Disney Zorro specials, Ricardo Montalban and Gilbert Roland. (Not counting actors who appeared in two movies in the same continuity, e.g. Douglas Fairbanks, Antonio Banderas, Catherine Zeta-Jones, and Tony Amendola.)