HBO is starting to pick up the pace when it comes to its casting decisions for the highly anticipated Harry Potter series, which is planned to be released in late 2026 or early 2027. So far, only John Lithgow has been officially confirmed to play Albus Dumbledore, but there have also been strong rumors linking Paapa Essiedu to Severus Snape and Janet McTeer to Minerva McGonagall.