Ivan Puluj (Іван Пулюй, also spelled Puliui) was a prominant physicist, electrical engineer, and inventor who discovered X-rays independently of Wilhelm Röntgen. He was born in Hrymaliv, Ukraine and graduated from the theology and philosophy departments of Vienna University in 1869 and 1972, respectively. In 1874 and 1875, he was lecturer of physics and mathematics in the Austrian Navy academy in Fiume (now Rijeka, Croatia). He continued his studies at the University of Strasbourg, where he obtained a PhD in 1876. He lectured at Vienna University and in Prague. Puluj also worked as a state adviser on electrical engineering for Bohemian and Moravian local governments.

He did extensive research into cathode rays, publishing several papers on the topic between 1880 and 1882. In 1881, through his experiments into what he called "cold light". This was effectively the same as X-rays, and he announced his results six weeks after Röntgen's report. He also invented a precise instrument for determining the mechanical equivalent of heat which was exhibited at the Paris Exposition Universelle in 1878. Author of 50 scholarly works in Ukrainian, German, and English. Together with P. Kulish and I. Nechui-Levyts’kyi, he translated the Psalms and Gospels from Hebrew and Greek, which became part of the Ukrainian Bible published by the British Bible Society (1903).