Godchildren are miserable human kids that have been deemed unhappy enough to receive fairy godparents. They keep their fairies until they are no longer miserable, or if they lose them due to a major violation of Da Rules, such as allowing their fairy to be revealed.
Tina Turner - lost her godparents Cosmo and Wanda when she grew up
Bill Gates - lost his godparents Cosmo and Wanda between 1970 and early 1972, when he was still a kid
Sammy - Former godchild of Cosmo and Wanda . However, he was one of their worst godchildren, as he wished for tornadoes to always strike mobile homes (or as he puts them "metal houses"). Cosmo and Wanda were taken away from him because of this and his picture is in the Hall of Infamy.
Pierre - Another godchild of Cosmo and Wanda. He is French, and in fact he was the one who wished all French people would be extremely rude to Americans. This is way he lost Cosmo and Wanda and why his picture is in the Hall of Infamy.
Maryann - Arguably one of the most dangerous of Cosmo and Wanda's former godchildren. Somehow, she managed to use their magic to cause the assassination of Archduke Ferdinand and that led to World War I. It is against the rules to use magic to kill someone, however it's possible that she was the reason the rule had to be implemented, or she indirectly manipulated it to cause the Archduke to be killed. Whatever the case, she clearly had planned to do it which is why she lost Cosmo and Wanda and why her picture is in the Hall of Infamy.
Walt Disney - lost his godparents Cosmo and Wanda when he grew up.
Erg - Appeared in The Past and the Furious. Cosmo and Wanda's first godchild, he lived during the prehistoric era and invented the wheel.
Megan Bacon - Appeared in The Past and the Furious, was the episode's antagonist. As a child she was rotten and wished to rule the world with bacon, and as a result of Timmy's interactions with her, she succeeded in an alternate timeline. However, after Timmy fixed his mistake she instead founded the Cake n' Bacon restaurant and was more or less a normal adult.
Artie Aaronson - A child pictured in the Hall of Fame.
Googie Sarakaya - A child pictured in the Hall of Fame.
Heather Wilson - A child pictured in the Hall of Fame. Notably, she resembles Vicky.
John - A child pictured in the Hall of Infamy.
Amelia Airhart - Mentioned in The Past and the Furious as being a former godchild for Cosmo and Wanda.
Mahatma Ghandhi - Mentioned in The Past and the Furious as being a former godchild for Cosmo and Wanda.