In Croatia, Marcius families are Croats (from Grubisno Polje ). In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and Grubisno Polje.
Prevalence
About 10 people with faimily name Marcius live in Croatia today, in five households only. There were 20 of them in the middle of the past century, and their number halved. They are located in three Croatian cities only: in Sveti Ivan Zelina (<10), Sesvete (<5), and in Vukovina (<5).
Outside Croatia
Family name Marcius is present in 14 countries worldwide.
In the sources analysed in the project Acta Croatica so far, the name is mentioned over ten times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.