Scandinavian, Low German and Czech form of Iohannes (see JOHN). (behindthename.com)
Still very Old European, conjuring up the image of a classical composer. But rising on the U.S. popularity list, largely thanks to Heidi Klum andSeal‘s young son. (nameberry.com)
Nicknames & Variations:
Johatan, Johathon, Johanan, Johathan, Joahan, Johanthan, Johannan, Johahn, Joannes, Johane, Johon, Johaun (nameberry.com)
Origin of the name Johan:Cognate of John (God is gracious), which is from the Middle Latin Johannes, an evolution of the Ecclesiastic Late Latin Joannes. Joannes is from the Greek Iōannes, a derivative of the Hebrew Yehanan, a short form of Yehohanan, which is from yehōhānān (Yahweh is gracious). The name, borne by several important biblical characters, was also borne by many saints, twenty-three popes, and many kings throughout Europe.From A World of Baby Names by Teresa Norman.
New Zealand Baby Names 