* Tom (or "Tom") - The barman of the Leaky Cauldron, who helps Harry find his way to Diagon Alley.
* Hagrid - The groundskeeper of Hogwarts, who is revealed to be Harry's giant half-brother and who brings him to the Leaky Cauldron.
* Professor Dumbledore - The Headmaster of Hogwarts, who meets with Harry and Hagrid in the Leaky Cauldron to reveal Harry's magical heritage and explain the events of his parents' deaths.
There are other patrons in the Leaky Cauldron, but these are the main characters that Harry interacts with.