pfft ! yeah, I know that, but the world of EU is nebulous beyond the realms Steve Swanseets little mind. Siv is 100% on the money...
Palpatine's full name (assuming he has any names other than "Palpatine" alone) has never been revealed. The usage "Emperor Palpatine" suggests that Palpatine is in fact his only name, though the use of titles such as "Senator Palpatine" suggests it may be his family name. Nevertheless, the original version of his character in Lucas's early scripts was named "Cos Da****" and many Star Wars fan fiction writers have quite incorrectly adopted the name "Cos Palpatine" in their stories and web pages -- so much so that it has become fanon. Of course, Palpatine might be a name of state, as the name Amidala is, so it may mean that neither Palpatine's given nor family name is known.
reference was here