HBO Max‘s first-look teaser for the much-anticipated “Harry Potter 20th Anniversary: Return to Hogwarts.”The preview, which aired Sunday night on TBS and Cartoon Network following the “Harry Potter: Hogwarts Tournament of Houses,” featured appearances from Robbie Coltrane (who played Hagrid), Matthew Lewis (Neville Longbottom) and Mark Williams (Arthur Weasley). The retrospective event premieres Jan.