Dictionary of Medieval Names
from European Sources

Hartmar m. Old Saxon hard, Old High German hart 'strong, hard' + Old High German, Old Saxon māri from Proto-Germanic *mērijaz 'famous'.

France
Latin
c823 Hartmarus (nom) irminon-vol2 42, CE
Cite as: S.L. Uckelman. "Hartmar". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2017, no. 1. http://dmnes.org/2017/1/name/Hartmar.