"We are absolutely thrilled that John Stamos is joining us on the series as Galavant's longtime rival — a dashing knight who squares off against him once more in a local joust," screenwriter-executive producer Dan Fogelman told ABC News in a statement. "We've wanted John to do an arc on this show since inception."

Stamos, known for his television work on "Full House," has been seen on Broadway in The Best Man, Bye Bye Birdie, Nine, Cabaret and How to Succeed…

As previously reported, "Galavant" will star Joshua Sasse as Galavant, Timothy Omundson as King Richard, Vinnie Jones as Gareth, Mallory Jansen as Madalena, Karen David as Isabella and Luke Youngblood as Sid.

Here's how it's described: "Once upon a time, the dashing hero, Galavant (Joshua Sasse) lost the love of his life, Madalena (Mallory Jansen), to the evil King Richard (Timothy Omundson). Now, our fallen hero is ready to take revenge and restore his 'happily ever after.' But it won't be without a few twists and turns along the way."

"Galavant" is written and executive-produced by Fogelman with executive producers Menken, Slater and Chris Koch, who directed. Abbey C Studios Ltd. produces "Galavant" for ABC Studios.