Which adjective is often given to Bavaria's King Ludwig II?

Which adjective can go before Britain, Dane and Gatsby? Which adjective goes before "Dog" in a Purina brand name? Which adjective describes Ken Kesey's band of Pranksters? Which adjective describes a condition that can't be treated by surgery? Which adjective is part of the name of Flash Gordon's enemy Ming? Which adjective describes someone who speaks English and two other languages? Complete the title of Eugene O'Neill's 1928 play: "___ Interlude". The 1890s are often nicknamed the "___ Nineties". Which adjective fills the blank?