The name Cathryn originates from the Greek language and culture, with its roots traced back to the late ancient period. It is a feminine variant of the name Katherine, which itself derives from the ancient Greek name Aikaterine. This name is composed of the elements "katharos" meaning "pure" and "heiros" meaning "sacred" or "holy."

In the medieval era, the name Cathryn gained popularity across Europe, particularly in regions influenced by the Byzantine Empire and the Eastern Orthodox Church. One of the earliest recorded instances of the name can be found in a 9th-century Byzantine text, where it was used to refer to a revered Christian martyr.

During the Middle Ages, the name Cathryn was adopted by several notable figures. One such individual was Cathryn of Siena (1347-1380), an Italian philosopher, theologian, and author who was canonized as a saint by the Catholic Church. Another was Cathryn Howard (c. 1521-1542), the fifth wife of King Henry VIII of England, who was beheaded for alleged adultery.

In the Renaissance period, the name gained further recognition with Cathryn de' Medici (1519-1589), an influential Italian noblewoman who served as the Queen Consort of France. Her political acumen and patronage of the arts left a lasting impact on French culture.

During the Reformation, the name Cathryn was embraced by Protestants, particularly in England and Scotland. One notable figure was Cathryn Parr (1512-1548), the sixth and final wife of Henry VIII, who played a significant role in promoting the English Reformation.

In the 17th century, Cathryn of Braganza (1638-1705), a Portuguese princess, became the Queen Consort of England, Scotland, and Ireland upon her marriage to King Charles II. Her influence helped to foster cultural exchange between England and Portugal.

Throughout history, the name Cathryn has been borne by various influential individuals, including Cathryn the Great (1729-1796), the renowned Russian Empress who presided over the Russian Enlightenment and expanded the Russian Empire; Cathryn Beecher (1800-1878), an American educator and activist who played a pivotal role in the early women's movement; and Cathryn Booth (1829-1890), the co-founder of the Salvation Army alongside her husband, William Booth.