How about Kor(t)(s)chno(i/j)
The most misspelled players of all time

I agree with Piphilologist.
Kortschnoj
Some others: Neal MacDonald
Adolph Anderson
Ulf Anderssen
John Lindsey MacCutcheon.
Here are some I have seen before:
Magnum Carsen
Booby Fisher
Nimzowitch, Nimzoswitch
Michael Botnik
William Steinitz
Fishy Anand

I misspelled "Nimzowitsch" in another thread at about the same time you created this thread. I caught my error almost immediately and changed it, though. I wonder if you caught my error?
Truth be told, I've seen his name spelled several ways in English in prominent books. After "Nimzo", you might see a V or W, and the TS or S can be optional (not that they should be).
For grins, I just googled "Nimzovich" and found a profile on Chess.com with that spelling. Check it out: the headline says "Aron Nimzovich", but the first sentence says "Aaron Nimzovich". So, even his first name is up for grabs.
http://www.chess.com/article/view/aaron-nimzovich

Here are some I have seen before:
Magnum Carsen
Booby Fisher
Nimzowitch, Nimzoswitch
Michael Botnik
William Steinitz
Fishy Anand
Actually William Steinitz is correct, originally Willhelm but then later called William.

The Russian ones (and others which use a different alphabet from English) are just transliterated spellings anyway, so I don't really see how they can have a 'correct' spelling with the English alphabet.
I think Carlsen/Carlson wins, he seems to be misspelled about one in three times. And his name isn't even transliterated, or hard in any way. And he's the world #1 player and he's still misspelled all the time by people who have no trouble writing Nepomniachtchi.
In reverse order, Miss World style:
5. Fischer, known to many as Fisher
4. Schlechter, a.k.a. Schlecter, Schleckter
3. Alekhine, affectionately known as Alkin
2. Rubinstein, who prompted the thread in fact. Rubenstein appears the most common version.
.... and now ... for the winner...
1. Nimzowitsch, actually had to look the spelling up.
[Edit: least misspelled - Tal]