Kat Marsden, born on May 13, 1859, and passed away on May 26, 1931, was a British missionary, explorer, writer, and nurse. She received support from Queen Victoria and Empress Maria Feodorovna to study a cure for leprosy.

Marsden undertook a journey from Moscow to Siberia and back to find a remedy for this disease, establishing a center for the treatment of lepers in Siberia. Upon returning to England, she contributed to the creation of the Bexhill Museum and was elected a member of the Royal Geographical Society. A large diamond is named in her honor, and she is still remembered in Siberia. In 2014, a memorial was erected in her honor in the village of Sosnovka. In 1890, she traveled approximately 11,000 miles (18,000 km) across Russia using trains, sleds, horses, and boats. During her journey, she assisted prisoners by distributing food and provided double rations to female convicts.

Shortly before her birthday in May, she arrived in Irkutsk and organized a committee to combat leprosy. She then traveled down the Lena River to Yakutsk, where she found a herb she believed to be a potential cure. Although the herb did not meet expectations, she continued to work with lepers in Siberia. In 1892, she became a member of the Royal Geographical Society, and Queen Victoria gifted her an angel-shaped brooch. In 1895, Marsden founded a charity now known as the St. Francis Leprosy Society.

In 1897, she returned to Siberia and opened a hospital for lepers in Vilyuysk, which operated until the 1960s. Each year, a scholarship named after Kate Marsden is awarded to the best student studying English at the M.K. Ammosov Northeast Federal University in Yakutsk.

On September 3, 2019, a monument to Kat Marsden, an international patron, was consecrated at the Hillingdon Cemetery in London. The initiative for the monument came from the residents of the Sakha Republic (Yakutia), who quickly raised funds and implemented the project. Kat Marsden is buried in plot YB42.