http://www.jewornotjew.com/profile.jsp?ID=864
The seven (at least part) Jewish chess champions are: Wilhelm Steinitz, Emanuel Lasker, Mikhail Botvinnik, Vasily Smyslov, Mikhail Tal, Bobby Fischer (BARF), and Garry Kasparov.
Anatoly Karpov and Vladimir Kramnik are rumored to be at least part Jewish, but those are likely just rumors...