"White" zebras actually encompass leucistic, blonde, and albino colorations
Actual true albino zebras are extremely rare...but there's a photo of one below.
Let's take a look:
Here's another picture of the true albino zebra:
Now check out this zebra...this zebra looks partially erased. He's among Grant's zebras, but his faded stripes look like a Burchell's or Chapman's zebra...
Interesting fact: There is a white zebra herd at Mt Kenya, Africa, which, when discovered in 1899, was afforded the protection of the British Crown. Here they are below: