Leibovich (leibowitsch) Ber (Boris) Abraham Kagan (14 June 1870, Shavli, Kovno Governorate – 1910, Kolomna) — physician.

Leibovich’s family moved to Riga shortly after his birth, and in 1891 emigrated to the United States, but he remained in Russia. He studied medicine at St Petersburg University and became an ophthalmologist. At the university he met Olga Shpakovskaya, a student at the medical faculty, whom he later married. Olga’s father, an influential local figure, helped them open a hospital in Kolomna. He also worked at the Krevyakin hospital. During the pogroms, Kagan Leibovich was repeatedly saved by peasant patients.

In 1901 and 1908, he visited New York, where his family lived. From 1908 to 1910, he worked in the United States at Sydenham Hospital. In 1910, he returned to Russia, where he died of typhus. According to an obituary published in Moskovskie Khroniki on 7 February 1910, the funeral procession stretched from Kolomna to Moscow.