1. Jack: This is his most common name, used by his friends, fellow newsies, and even some of the adults he interacts with.
2. "The Kid": This nickname is used by the older newsies, acknowledging his youth while also implying a certain level of respect for his leadership qualities.
3. "Jack Kelly": This is his full name, typically used in more formal settings or when he's trying to make a point or assert himself, often used when interacting with the authorities.
While he may be called by other variations (like "Jacko," "Kelly," or even "Kid Kelly"), these three are the most significant and recurring names throughout the show.