Namesakes
Dutch Prime Ministers:
1 prime minister
Justinus van der Brugghen 1856-1858 
Nobel Prize Winners:
1 physics
(physics) Martinus J. G. Veltman (a.k.a. Justinus) 1999
Notable Scientists and Inventors:
1 physicist
Martinus J. G. Veltman (a.k.a. Justinus) 1931-2021
Roman and Byzantine Emperors:
2 emperors
Emperor Flavius Justinus (a.k.a. Justinus) 518-527
Emperor Flavius Justinus Junior (a.k.a. Justinus) 565-578