Queen Elizabeth II's nickname, Lilibet, was given to her by her father, King George VI.
The nickname originated from Elizabeth's inability to pronounce her own name as a child. She struggled to say “Elizabeth” and instead called herself “Lilibet.”
The nickname was reportedly used by her family and close friends throughout her life. It is a term of endearment that reflects the close bond between the King and his daughter.
While the nickname was never officially adopted by the public, it remained a cherished part of the Queen's personal life.