Well of course even in English it's also written with a capital letter. I'm guessing that the change in the last syllable was done because English pronunciation would tend to put 'zch' together and say "...stiljen". It's pronounced quite differently in Eng. and Ger. however!

Isn't it "Rumpelstiltskin" in English?

arbeD: Considering that there are 19,000 hits to 73, you certainly seem to be right.