No European country has as many names as Germany.
'Deutschland' comes from Old High German 'diutisc', 'of the people'. English says Germany after Latin Germania, French and Spanish say Allemagne/Alemania after the Alemanni tribe, Finns say Saksa after the Saxons. Poles say Niemcy, from Slavic 'němec', 'the mute one': people you can't understand.
Useful: Most neighbours named the country after the tribe they met first.
Source: en.wikipedia.org