Tadeáš Hájek, Czech physician and astronomer (d. 1600)
Tadeáš Hájek z Hájku (Czech pronunciation: [ˈtadeaːʃ ˈɦaːjɛk ˈzɦaːjku]) (1 December 1525 in Prague – 1 September 1600 in Prague), also known as Tadeáš Hájek of Hájek, Thaddaeus Hagecius ab Hayek or Thaddeus Nemicus, was a Czech naturalist, personal physician of the Holy Roman Emperor Rudolph II and an astronomer in the Kingdom of Bohemia.