Prince William's son Prince George has reportedly nicknamed his great-grandmother "Gan-Gan."
The Queen is also known as "Lilibet," though it's also been reported that Prince Philip has referred to her as "sausage" in the past.
She's referred to as "Mama" by many members of the Royal Family as well.
Meghan Markle may be the newest member of the Royal Family, but she's already earned a nickname courtesy of Prince Charles.
He reportedly calls her "Tungsten" after the metal due to her "tough and unbending" nature.
Kate Middleton and Prince William also both refer to each other as "darling" and "babe," per overheard conversations between the Royal couple.
Both Prince William and Prince Harry have used various code names throughout their lives in an attempt to disguise their identities.
Prince Harry, who was thought to have been called "Spike" in his youth, has also been rumoured to have a Facebook account under the name "Spike Wells," a name he's also reportedly used in general to avoid attention by the media and general public.
He's also believed to have been nicknamed "Hazza" by Meghan Markle's friends.
Prince William has also gone by other names in order to avoid detection. While studying at the University of St Andrew's in Scotland, he picked out "Steve" as a name to disguise his real identity.