What should i wear to my own 17th birthday party?

hi, im turning 17 in may and me and my 2 best friend are having one big birthday dress up party. the theme is hollywood glamour...one of my m8z id going as marilyn monroe and the other one is going as twiggy, i have no idea want i want to go as maybe madonna or gwen stefani i want to go as some kind of hollywood icon but i dont want it to be one of the new ones on at the mo...so can anyone help me out with who i should go as and what 2 wear????