Namesakes
Islamic Caliphs:
2 caliphs
Caliph Umar ibn Al-Khattab 634-644 Rashidun 
Caliph Umar II ibn Abd al-Aziz 717-720 Umayyad
Notable Philosophers and Thinkers:
1 mathematician
Omar Khayyám (a.k.a. Umar) 1048-1131
Notable Writers:
1 poet
Omar Khayyám (a.k.a. Umar) 1048-1131