Tall, strong, and blonde, Cato is the Capitol definition of good-looking. Okay, so he doesn't look the smartest, but as far as he's concerned, looking smart doesn't matter if you can look good. He's not vain but he does make a conscious effort to dress to emphasise his physique, which as you can imagine, pretty fit. Because he spends a lot of time outside - whether he's supposed to or not! - his skin has developed a permanent light tan. His facial feautures are thickset and his eyes are blue. At 6'2", he's only smaller than Thresh, who can almost compare to him in muscle, I guess.
Cato is not as stupid as he looks. He's not intelligent in the sense that he'd do well in school, but his insticts are are solid and good at making quick decisions.