Robert Saitschick or Robert Saitschik (Russian: Рувим Маркович Зайчик; April 24, 1868, Mstsislau, Russian Empire – February 23, 1965, Horgen) was a Swiss philosopher. He grew up in Warsaw, where his father Morduch Zaitchik became a merchant. After graduating from the 8th grade of the 5th Warsaw gymnasium he became a member of a revolutionary circle, which led to a legal action against him in 1887 over spreading of a revolutionary poem. He left Warsaw in late December of that year and moved to Vienna.