Nikolai Vladimirovich Dahl, often called Nicolai Dahl (Russian: Николай Владимирович Даль) (July 17, 1860 – 1939) was a Russian physician.[1] He is most notable for his successful treatment of the composer Sergei Rachmaninoff, who was suffering a creative block after the disastrous premiere of his First Symphony. Among his other notable patients were Chaliapin, Scriabin, Stanislavsky, and many others.