List of communist Jews:

Mosa Pijade: Yugoslavia
http://en.wikipedia.org/wiki/Mo%C5%A1a_Pijade
http://www.jewishvirtuallibrary.org/jsource/judaica/ejud_0002_0016_0_15763.html
"He was helpful in allowing the departure of Jews to Israel with all their personal property and gave occasional advice to the leaders of the Federation of Jewish Communities."

Roman Zambrowski: Poland (vice-president of the Supreme Chamber of Control)
http://en.wikipedia.org/wiki/Roman_Zambrowski
"was a Polish-Jewish communist activist. He is the father of journalist Antoni Zambrowski.
Zambrowski was born into a Jewish family"

Rudolf Slánský: Czechoslovakia ("the second most powerful man in the country behind president Gottwald")
http://en.wikipedia.org/wiki/Rudolf_Sl%C3%A1nsk%C3%BD
http://www.britannica.com/EBchecked/topic/548065/Rudolf-Slansky
"he was Jewish, at a time when, through the Eastern bloc, influenced by the USSR, Jewish leaders were being used as scapegoats for shortages and economic problems"
"Slánský and 10 of his 13 codefendants were Jewish"

Ana Pauker: Romania (Minister of Foreign Affairs)
http://en.wikipedia.org/wiki/Ana_Pauker
http://jwa.org/encyclopedia/article/pauker-anna
"Pauker was born into a poor, religious Orthodox Jewish family of merchants in Codae?ti, Vaslui County"

Karl Marx: German (Philosopher)
http://en.wikipedia.org/wiki/Karl_Marx
Nicolaievsky and Maenchen-Helfen 1976, pp. 4–6; McLellan 2006, pp. 2–4.
Karl Marx was born on 5 May 1818 to Heinrich Marx and Henrietta Pressburg (1788-1863). He was born at 664 Brückergasse in Trier, a town then part of the Kingdom of Prussia's Province of the Lower Rhine. Ancestrally Jewish, his maternal grandfather was a Dutch rabbi, while his paternal line had supplied Trier's rabbis since 1723, a role taken by his grandfather Meier Halevi Marx. Karl's father, as a child known as Herschel, was the first in the line to receive a secular education; he became a lawyer and lived a relatively wealthy and middle-class existence, with his family owning a number of Moselle vineyards. Prior to his son's birth, and to escape the constraints of anti-semitic legislation, Herschel converted from Judaism to Lutheranism, the main Protestant denomination in Germany and Prussia at the time, taking on the German forename of Heinrich over the Yiddish Herschel"

Mátyás Rákosi: Hungary (Chairman of the Council of Ministers of the People's Republic of Hungary)
http://en.wikipedia.org/wiki/M%C3%A1ty%C3%A1s_R%C3%A1kosi
"Rákosi was born in Ada, then a village in Bács-Bodrog County in the Kingdom of Hungary (one of the two monarchies that at the time constituted The Dual Monarchy of Austria-Hungary), now a town in Vojvodina, Serbia. Born into a Jewish family, the fourth son of a grocer (his mother would give birth to seven more children), he later repudiated religion and totally repudiated Judaism."

Erno Gero:Hungary (Chairman of the Council of Ministers of the People's Republic of Hungary)
http://en.wikipedia.org/wiki/Ern%C5%91_Ger%C5%91
"Gero was born in Terbegec, Hungary (now Trebušovce, Slovakia) to Jewish parents, though he later totally repudiated religion."

János Kádár: Hungary (Chairman of the Council of Ministers of the People's Republic of Hungary/Minister of the Interior of Hungary)
http://en.wikipedia.org/wiki/J%C3%A1nos_K%C3%A1d%C3%A1r
"He was appointed deputy because of social and ethnic background, the majority of the leadership were of Jewish origins and were intellectuals"

Yuri Andropov: USSR (Chairman of the Presidium of the Supreme Soviet of the Soviet Union/4th Chairman of the Committee for State Security (KGB))
http://en.wikipedia.org/wiki/Yuri_Andropov
"Andropov was born in Nagutskaya, Stavropol Region, Russian Empire, on 15 June 1914.He was the son of a railway official, Vladimir Konstantinovich Andropov, who was of a Don Cossack family and Yevgenia Karlovna Fleckenstein, the adopted daughter of a Moscow watchmaker, Karl Franzovich Fleckenstein, who was originally from Finland."

Lev Kamenev: USSR (Deputy Chairman of the Council of People's Commissars of the Soviet Union/Chairman of the Central Executive Committee of the Congress of Soviets of the Russian SFSR)
http://en.wikipedia.org/wiki/Lev_Kamenev
"Kamenev was born in Moscow, the son of a Jewish railway worker and a Russian Orthodox mother. The wealth that his father had acquired in the building of the Baku-Batumi railway was used to fund a good education for Lev"

Grigory Yevseevich Zinoviev: USSR
http://en.wikipedia.org/wiki/Grigory_Zinoviev
Gregory Zinoviev was born in Yelizavetgrad, Russian Empire (now Kirovohrad, Ukraine), to Jewish dairy farmers

Vyacheslav Molotov: USSR (Minister of Foreign Affairs)
http://en.wikipedia.org/wiki/Vyacheslav_Molotov
"In the postwar period, Molotov's power began to decline. A clear sign of Molotov's precarious position was his inability to prevent the arrest in December 1948 for "treason" of his Jewish wife, Polina Zhemchuzhina, whom Stalin had long distrusted."

Polina Zhemchuzhina USSR (propaganda commissar)
http://en.wikipedia.org/wiki/Polina_Zhemchuzhina
"Born Perl Karpovskaya to the family of a Jewish tailor in the village of Pologi,"

Maxim Litvinov: USSR (Soviet Ambassador to the United States)
http://en.wikipedia.org/wiki/Maxim_Litvinov
"Born Meir Henoch Mojszewicz Wallach-Finkelstein (simplified into Max Wallach, Russian: ???? ??´????) into a wealthy Litvak (Jewish) banking family in Bialystok, Grodno Governorate of the Russian Empire"

Konstantin Umansky USSR (Soviet Ambassador to the United States)
http://en.wikipedia.org/wiki/Konstantin_Umansky
(Gilboa, Jehoshua A. (1971). The black years of Soviet Jewry, 1939-1953. Little, Brown. p. 246. Retrieved 2009-08-01.
Jump up ^ Low, Alfred D. (1990). Soviet Jewry and Soviet policy. East European Monographs. p. 4. ISBN 0-88033-178-X. Retrieved 2009-08-01.)
"Umansky, who was Jewish, was born in Mykolaiv;"

Andrei Gromyko: USSR (Minister of Foreign Affairs)
http://en.wikipedia.org/wiki/Andrei_Gromyko
"On May 14, 1947, Gromyko introduced the idea of partitioning Palestine into a Jewish state of Israel and an Arab state of Palestine"


Józef Pilsudski: Poland (Chief of State of the Second Republic of Poland)(Planned and carried out the Bezdany raid)
http://en.wikipedia.org/wiki/Bezdany_raid
http://en.wikipedia.org/wiki/J%C3%B3zef_Pi%C5%82sudski
"The years 1926–35, and Pilsudski himself, were favorably viewed by many Polish Jews whose situation improved especially under Pilsudski-appointed Prime Minister Kazimierz Bartel. Many Jews saw Pilsudski as their only hope for restraining antisemitic currents in Poland and for maintaining public order; he was seen as a guarantor of stability and a friend of the Jewish people, who voted for him and actively participated in his political bloc."
"His death was a shock to members of the Jewish minority, who even years after remembered him as a very good man who protected Jews"

Nikolay Burenin: USSR (member of the Russian Social Democratic Labour Party)(Planned and carried out the 1906 Helsinki bank robbery)
http://en.wikipedia.org/wiki/Nikolay_Burenin
http://en.wikipedia.org/wiki/1906_Helsinki_bank_robbery
"Burenin was born in Saint Petersburg into a wealthy merchant family."

Maxim Gorky: USSR (openly associated with the emerging Marxist social-democratic movement)(Reciver of the funds from the 1906 Helsinki bank robbery)
http://en.wikipedia.org/wiki/1906_Helsinki_bank_robbery
http://en.wikipedia.org/wiki/Maxim_Gorky
"n 1916, Gorky said that the teachings of the ancient Jewish sage Hillel the Elder deeply influenced his life"

Vyacheslav von Plehve: Russia
http://en.wikipedia.org/wiki/Vyacheslav_von_Plehve
"In August 1903 he met with Theodor Herzl in Saint Petersburg, discussing the establishment of Zionist societies in Russia and proposed a Russian government request to the Turks to obtain a charter for Jewish colonisation of Palestine.

Yevno Azer: Russia
http://en.wikipedia.org/wiki/Yevno_Azef
"Born as Evno Fishelevich Azef in Lyskava (now Brest Region, Belarus) in 1869 to a poor Jewish family. He was the second of seven children."
"he embezzled 800 rubles"

Hirsh Lekert: Russia
http://en.wikipedia.org/wiki/Hirsh_Lekert
"Hirsh Lekert (born 1880 in Onuškis (Hanoshishok), near Kaunas,[1] died June 10, 1902 in Vilna[2]) was a Jewish socialist activist and member of the Bund."

A widly expanded list for those who are too lazy to dig on their own:
http://en.metapedia.org/wiki/List_of_communist_Jews