Guillermo is a Spanish masculine given name derived from the Germanic name Wilhelm, meaning "resolute protector" or "strong-willed warrior." It is a popular name in Spanish-speaking countries and is often shortened to "Guille" or "Memo" as a nickname. Guillermo is frequently used in honor of Saint William, who was an English bishop and missionary known for his dedication to spreading Christianity. People named Guillermo are often described as strong, confident, and dependable individuals with a natural leadership ability. Overall, Guillermo is a name that conveys strength, determination, and a strong sense of protection for those they care about.