I've gotta say I have TWO favorites, and both are carried out by young Vito in GFII.

First when he shoots Fanucci; a brilliantly planned and perfectly executed hit - all by ONE man! He let NO ONE else in on what he was going to do!!!!

Second is the revenge killing on Don Ciccio in Italy. Love the way he inserts and slides that knife, then gives the body that disgusted shove before walking away.

Apple