Work begins on second season of Harry Potter HBO boss Casey Bloys has revealed work on the second series of Harry Potter is already under way. 30 March 2026 Work has already begun on the second series of Harry Potter. The young stars of Harry Potter Last week, the first trailer for HBO's upcoming blockbuster wizarding series - which is based on JK Rowling's best-selling novels - debuted along with the announcement the programme will now premiere at Christmas this year, and fans won't have to wait too long for the follow-up episodes.