In the world, Mercius (Mercius 
) is a very rare boy's forename. The given name Mercius is habitual in the Dominican Republic, where it is a rare male name, and the United States, where it is an extremely rare boy's name. More prevalently, Mercius is the last name as well as the forename.
| VARIANT | COUNTRY |
|---|---|
| Mercius | Dominican Republic, United States, Haiti, France, Brazil |
Marc, Rosena, Roodly, Gemima, Lidieu, Joseph, Jeanne, Nadine, Emilio, Herode, Ismael, Odline, Wisler, Yvrose, Miranda, Sherley, Kerline, Kernesuze, Gileine, Natasha, Nelkens, Yvenise, Pierre, Kerne-Suze, Kalina, Aronce, Rose, Rony, Dean, Lisa, Jean, Yvel, Marie, Milor, Sarah, Kenan, Mirlande, Kenol, Regis, Ridza, David, Jacky, Nadia, Elias, Itela, Waldy, Michel, Simeon, Kerne, and Chrisnel