Red Grant's cool professionalism all throughout is a beauty to behold. He stalks Bond through the whole movie, even saving his life once, with Bond none the wiser. Then, he has the balls to kill Bond's contact, replace him to fool Bond. And Bond is totally fooled until Grant reveals himself as SPECTRE.
His introduction to Rosa Klebb, where he no sells getting hit in the gut with brass knuckles.
Bond manages to kill the totally brutal Red Grant with his own wristwatch-garotte. He then retrieves his money and incriminating film from Grant's pockets, growling "You won't be needing this...'old man.'" Yeah.
Not to mention the fight between them, one of the most well known in cinematic history of its tense brutality.