The actor in question is Jack Wyatt, played by Will Ferrell, who is cast as the male lead in the remake of Bewitched. Jack is a washed-up movie star who is desperate to revive his career by taking on a TV project. He convinces the producers to cast an unknown actress as the female lead, as he believes he can easily outshine her and make himself the star of the show.
The unknown actress is Isabel Bigelow, played by Nicole Kidman, who is actually a witch. Isabel is unaware that Jack is using her as a stepping stone to further his own career, and she soon falls in love with him. However, her magic powers start to interfere with the production, causing havoc on set and making it difficult for Jack to maintain his status as the lead actor.
As Isabel becomes more involved in the production, she starts to realize that the TV show is not just a means to an end for Jack, but something that she enjoys doing as well. However, her interference and the chaos she causes puts the production at risk, and Jack starts to resent her presence on set.
Meanwhile, Isabel's father, Nigel Bigelow (played by Michael Caine), is strongly opposed to her involvement in the show, and tries to convince her to give up her dream and return to their magical world.
The movie is a mix of comedy, romance, and fantasy, with a meta approach to the original Bewitched TV show. It highlights the struggle of a woman who wants to pursue her dreams while dealing with an increasingly difficult and selfish male co-star. The ending sees Jack beginning to appreciate Isabel's talents as a witch and the two of them finally working together to make the show a success.