The name Kathy is a diminutive form of the name Katherine, which is derived from the ancient Greek name Aikaterine. This Greek name itself came from the combination of two words: "katharos" meaning "pure" and "heiros" meaning "sacred." The name Katherine was initially popularized in the early Christian era and has been widely used across various cultures and regions.

Kathy is believed to have originated as a pet form or nickname for Katherine during the Middle Ages, particularly in England and other parts of Europe. The earliest recorded use of the name Kathy can be traced back to the 16th century, where it was a common shortened version of Katherine used among the English nobility and upper classes.

One of the earliest known historical figures with the name Kathy was Katharine Willoughby, Duchess of Suffolk (1519-1580), a prominent English noblewoman and Protestant reformer during the reign of Queen Elizabeth I. Another notable figure was Katharine Parr (1512-1548), the sixth and final wife of King Henry VIII of England.

In the realm of literature, the name Kathy appears in works such as "Wuthering Heights" by Emily Brontë, where the character of Catherine Earnshaw is affectionately called "Cathy" by her love interest, Heathcliff. This novel, published in 1847, helped popularize the diminutive form of the name.

During the 20th century, several famous individuals bore the name Kathy, including Kathy Bates (born 1948), the American actress and recipient of an Academy Award for her role in the film "Misery"; Kathy Najimy (born 1957), an American actress and comedian known for her roles in films like "Sister Act" and "Hocus Pocus"; and Kathy Reichs (born 1948), a renowned American crime writer and forensic anthropologist.

Additionally, Kathy Ireland (born 1963) is a former American model and actress who later became a successful entrepreneur and author, while Kathy Griffin (born 1960) is an American comedian and actress known for her stand-up comedy and television appearances.