I main Diana and Fizz. What other champs would be similiar.

Look no further

Same kind of ult as Diana, defensive W (shroud), and assassin play-style. As someone else mentioned is a good one too and to some extent and are other assassins with similarities but a lot of difference, might want to give them a shot when they're free to see if you like them.

Well, Galio is the last of the only three champions that can beat leblanc in lane.

The only archetype that can compare to Diana is another Fighter, mainly one with a Sword.