Although it was never addressed, Newt Scamander from Fantastic Beasts and Where to Find Them briefly appeared in Harry Potter and the Prisoner of Azkaban. Taking place during the 1920s through to the 1930s, the Fantastic Beasts and Where to Find Them movies serve as a prequel series to the Harry Potter films. As such, the Fantastic Beasts movies include references and some characters who crossover to Harry Potter. In contrast, the Harry Potter movies include very few references to Fantastic Beasts and Where to Find Them, which makes sense given that the Harry Potter films were created first. However, one notable Easter egg was when Newt Scamander appeared on the Marauder’s Map in Harry Potter and the Prisoner of Azkaban.
https://screenrant.com/newt-marauders-map-harry-potter-theory/