A l i k e n e s s
The right pic is the one that looks most like Quatre. The left one is the character's most recognizable pic.
T O H M A S E G U C H I
Are you seeing double? Absolutely not! This is Tohma from Gravitation. I came across this while I was looking at a site that suggested this clone. I'm well aware that this anime contains yaoi. But I just wanted other people to know that there's really a Quatre clone out there! What's even more surprising is, both Quatre and Tohma's voices are done by Orikasa Ai!!
P R I N C E C H I D
Another clone suggested by some. Prince Chid from Vision of Escaflowne looks exactly like a mini version of Quatre! He is a real prince. X_x Chid is always struggling to do the right thing for the benefit of his kingdom. Quatre is somewhat like that, since he always struggles to do what is right in this era of war.
Y U G I M O T O
They don't look alike, but they act very alike though. Yugi from Yu-Gi-Oh always helps his friends when they are in trouble. Both Quatre and Yugi have very kind souls. They would never try to hurt anyone. But when the spirit of the millenium puzzle takes over Yugi, it resembles Quatre being taken over by the Zero System. They both started to lose it and go "crazy" because they're afraid that someone will get hurt.