Is there a word for special names given to people of a certain group [duplicate]

Examples:

• People who work at Google are called "Googlers"
• Fans of the Green Bay Packers are called "Cheese heads"
• Readers of Robinhood enewsletter are called "Snackers"
• Hardcore fans of Harry Potter are called "Potterheads"

These are just several examples. This question was inspired by this tweet.

Solution 1:

A term for people belonging to a particular place is called a "denonym":

A demonym or gentilic is a word that identifies residents or natives of a particular place, usually derived from the name of the place or that of an ethnic group.… Examples of demonyms include Cochabambino, for someone from the city of Cochabamba; American for a person from the country called the United States of America; and Swahili, for a person of the Swahili coast.