Famous athletes who have same initial for first and last name...to honor ZiZou!
B: Boris Becker (tennis)
D: David Duval (golf)
J: Jimmie Johnson (NASCAR)
P: Peter Parker (LOL)
U: Ugueth Urbina (baseball pitcher, not famous per se but still quite well known in baseball circles)
W: Will Witherspoon (NFL linebacker)
Z: The one, the only Zinedine Zidane
I'm sure there are more for popular characters like T, S, F, N etc but for X, Y, Q etc that might be a tough call...