The Kanji in the Japanese name of Ken Panzer, 堅 (On: ken/Kun: katai), means hard, whose on'yomi is the origin of 'Ken' as well. It is also in response to Co Tanker's Kanji forming the Japanese term for hard, 堅硬 (kenkou). 'Panzer' is the German for tank.
Ken Panzer was once named 'Tank' (タンク,Tanku?) tentatively.