Gero and his company are probably best known for the animal supervision on the Harry Potter films Harry Potter and the Sorcerer's Stone (2001), Harry Potter and the Chamber of Secrets (2002), Harry Potter and the Prisoner of Azkaban (2004), Harry Potter and the Goblet of Fire (2005), Harry Potter and the Order of the Phoenix (2007), and Harry Potter and the Half-Blood Prince (2009). [1] [2]