Who are some famous German composers?

Tokio Hotel

http://tokiohotel.pop24.de/tokiohotel2/index2_de.php although im not the biggest fan of tokio hotel they do have some good songs

There is also a band named

Rammstein which is a (tanz metal/ industrial) band

and another that woul be considered goth rock named Lacrimosa sorry for lack of refference on those two.