Gregorio Zeppeli is Gyro's father and an executioner of the nation of Naples.
Gregorio is a man who lives his life apart from sentimentality. He never makes personal friends, never owns pets, he avoids visiting people and going to weddings and he spent dinner only with his family. He also does not allow pictures to be taken. He never writes letters or keeps a journal, never gives of receives presents. This is because he believed that memories of human relationships led to sentimentality and weakness.
Gregorio would often tell his eldest son that the Zeppeli family was in the hands of the monarchy and that it was not in the position of the monarch's subordinates to be sentimental. On the other hand, he had complimented his son's sentimentality when the latter had tried to use his spin abilities to cure Wekapipo's sister and failed, stating that restoring her sight fully would have consequences that would cause her family-in law to hunt her down and kill her.
Gregorio instructed Gyro in the use of Steel Balls training him to become a skilled executioner. Although the Zeppeli family usually stuck to delivering the death penalty to serious and dangerous criminals, there was one incident which resulted in the arrest and death sentence of an innocent little boy who made a living from cleaning shoes. Gyro was struck when he heard of this and even more when the boy offered to clean his own executioner's shoes.
Gregorio was strictly convinced that the Zeppeli family are in the hands of the state and aren't the ones who choose whether or not someone dies. Refusing this, Gyro pleaded with the king for an appeal. It was then agreed that Gyro would receive an amnesty to release the boy if he could complete the American cross-country race, the Steel Ball Run.
After Gyro's death, the Zeppeli family leaves Naples.