how many champs have first and last names?

Shauna Vayne Luxanna Crownguard Garen Crownguard Katarina Du Couteau Talon Du Couteau Cassiopeia Du Couteau Fiora Laurent Malcolm Graves Annie Hastur Morgana Hex Yorick Mori (one of his quotes= "You will remember Yorick Mori.") Matt LeBlanc (its actually Emilia) Jarvan Lightshield the Fourth

3 more in addition to what others have mentioned: Janna Windforce Khada Jhin Xin Zhao

Professor Cecil B. Heimerdinger, The Revered Inventor.

Shen Kusho, I believe would count as one, unless Ionians use a rule of (title) (first name) rather than (title) (surname).

Talon doesn't have a last name, unless he goes by his master's name.