One of the most popular methods of formation of one-stem proper names is derivation. The present work studies in brief the suffixes with which in Old High German and Old Bulgarian Slavic male proper names were derived in the period of VI — XII century. The suffixes are either diminutive or non-diminutive. Some have a common Indo-European origin and identical functions in the two onomastic systems, others do not have these features. On the whole, the Old Bulgarian male one-stem names were derived from a greater variety of suffixes than those in Old High German.