Seraya Shapshal or His Excellency Hajji Seraya Khan Shapshal  (Karaim: Серая Бен Мордехай Шапшал; Russian: Серге́й Маркович Шапшал; Polish: Seraj Szapszał) (1873-1961) was a hakham and leader of the Crimean and then the Polish and Lithuanian Crimean Karaites (Karaim) community.
Shapshal was born in Bahçesaray, Crimea and studied at St. Petersburg University, where he was graduated in philology and oriental languages. During his studies he became a strong adopter of Russian orientalist V.Grigorjev's theory about Crimean Karaites Khazarian origin. Immediately after his graduation at 1901 he was invited to serve as the personal tutor of the Iranian crown prince, Mohammad Ali Shah, and became a minister in the Persian government in 1907 (actually he was a Russian spy). In 1911 he returned to Crimea and became Chief Hakham of the Crimean Karaites communities in Crimea.
From 1920 to 1927 he lived in Istanbul. Here he was active in the pan-Turkic movement. In 1927 while living in Turkey he was elected the head of the Karaims in Poland and in 1928 moved to Wilno.
He denied any connection between Crimean Karaites and Rabbinic Jews.Shapshal is the founder of the Crimean Karaites religion and history Dejudaization Doctrine. Under this doctrine, he changed the traditional title of "Hacham" to "Gahan", rising in his opinion to the Khazarian word ""Khagan". In the mid 1930s, he began to create a theory of the Altai-Turkic origin of the Karaims and the pagan roots of the Karaite religious teaching (worship of sacred oaks, polytheism, led by the god Tengri, the Sacrifice). Shapshal's doctrine is still a topic of critical research and public debate.
He made a number of reforms aimed at Karaims Turkification and destruction Karaite Jewish elements of culture and language. He issued an order canceling the teaching of Hebrew in Karaite schools, replaced the name of the Jewish holidays and the months by the Turkic one, the position of "Hacham" renamed "Gahan" in consonance with the word "khan", invented in this special custom taking office, allegedly accepted the Khazars. According Shapshal, the doctrine of Anan ben David was close to early Christianity, and Karaites believed for centuries in Jesus and Mohammed as prophets. Crimean Karaites adopted the law of Moses, but continued to adhere to the ancient Turkic pagan beliefs.
Between efforts to approve Crimean Karaites Khazarian origin was their history "militarization" process originated in the 20th century inter-war Poland  -the trend to represent for the Karaite population of Eastern Europe as a nation of warriors. Shapshal was one of this process initiators.
In 1939 using his connections in Russian emigrants community in Germany, he appealed to the racial authorities in the Reich Biureau of the Ministry of Internal Affairs with a request to examine the issue of Crimean Karaites ethnicity. After German troops occupation of Crimean Karaites populated areas in Eastern Europe this appellation was considered by German administration. They involved three major historian specialist on the history of the Karaites - Zelig Kalmanovich, Meir Balaban and Yitzhak (Ignacy ) Schiper. Despite the fact that all three had been before the war, a fierce opponents of the Crimean Karaites Turkic origin theory, they supported the Shapshal's theory to save European Karaites from the Holocaust . Shapshal was instrumental in the formulation of Nazis policy towards the Karaims. As Hakham of Vilnius he was infamous for his confrontations with such Jewish community figures as Zelig Kalmanovich. He was also known for having been forced (under penalty of endangering his own community) to give to the Nazis a detailed list of the members of the Crimean Karaites communities of Troki and Vilnius, allowing them to easily discover and arrest Jews who had forged papers stating that they were Crimean Karaites.
In 1945, formally abdicated from Karaite Gahan post, submitting a statement to the Commissioner for Religious Affairs, the Council of Ministers of the Lithuanian SSR and got the position as a researcher at the Institute of History of the Soviet-dominated Lithuanian Academy of Sciences
Using his position he continued to promote his ideas including forgery  of some evidences, regarding military past of Crimean Karaites, publishing the articles about his "discoveries" in the Soviet Union's leading academic journals. Shapshal's archive recent studies have shown that his drafts include several versions of the "original" documents texts  evidencing forgery. In spite of that Shapshal's ideas about Karaim warriors were adopted widely in USSR and even abroad. Thus in modern Lithuania Trakai visitors are often guided that Karaim warriors were guards of Trakai Castles. In 1997 souvenir coin in denominations of 50 LTL was issued in honor of the 600th anniversary of the Tatars and Crimean Karaites in Lithuania. The coin includes the image of Tatar and Karaim warriors.
Some his works including "History of the Karaims" remains unpublished. Part of his collections and books are kept in National Library of_Lithuania the other in a small museum in the old kenesa of Troki, where he died in 1961.
- «Jego Exellencja Szapszał Hadży Seraja Han»is the way he called himself in Polish //Archiwum Akt Nowych, Ministerstwo Wyznań Religijnych i Oświęcenia Publicznego (Варшава). Д. 1464. Л. 30, 97.
- Browne, E. G. The Persian Revolution of 1905-1909. Cambridge, 1910. С. 105, 130, 170-171, 198-200, 202, 207, 214,279, 324, 418-420
- Roman Freund «Karaites and Dejudaization» (Acta Universitas Stockholmiensis. 1991. - №30).
- (Nowachowicz Z. Witaj, Pasterzu! // Myśl Karaimska:4—5 (1928). — S. 1—4; J.E.H. Seraja Bej Szapszal // Myśl Karaimska:4—5 (1928). — S. 5—7) comparing with (List Pasterski J.E.Hachana Karaimyw w Polsce // MK 2:1 (1929). — S. 3—4)
- М. Кизилов, «Новые материалы к биографии Шапшала»// Материалы девятой международной конференции по иудаике (2002), с. 255—273.
- Кизилов М. Ильяш Караимович и Тимофей Хмельницкий: кровная месть, которой не было, Karadeniz Araştırmaları, Cilt: 6, Sayı: 22, Yaz 2009, C.43-74.
- Shapira D. Polish Sarmatism, Turkism, and ‘Jewish szlachta’: Some Reflections on a Cultural Context of the Polish-Lithuanian Karaites // Karaites in Eastern Europe in the Last Generations.Proceedings of the Jerusalem Karaite Colloquium, Ben-Zvi Institute and the Center for the Study of Polish Jewry and its Culture. Ed. D.D.Y. Shapira. Jerusalem, 2008
- Шапшал С. М. О прибывании Богдана Хмельницкого и его сына Тимофея в Крыму, // Вопросы истории № 8, 1955, Письма и заметки.
- Ingmar Karlsson.The Karaim and the Gagauz - the Jewish and the Christian Turkic peoples- a lecture given at the Swedish Research Institute in Istanbul on February 22 2006
- Shapshal, S. M.: Karaimy SSSR v otnoshenii etnicheskom: karaimy na sluzhbe u krymskich chanov. Simferopol', 2004
- Kizilov M. New Materials on the Biography of S. M. Szapszał in 1928-1939 // Материалы Девятой Ежегодной Международной Междисциплинарной Конференции по Иудаике. – М., 2002. – Ч. 1. – С. 255–273
- Shapira Dan D. Y. A Jewish Pan-Turkist: Seraya Szapszał (Şapşaloğlu) and his Work Qırım Qaray Türkleri (1928) (Judaeo-Türkica XIII) // Acta Orientalia Hungaricae. – December 2005. – Vol. 58, № 4. – P. 349–380
- Зайцев И.В. «Что мне делать и как быть?» (письма Серайя Марковича Шапшала академику В.А.Гордлевскому: 1945-1950) // Вестник Евразии. Acta Eurasica. № 4 (38). М., 2007. С.147-169
- Петров-Дубинский О.В. С.М.Шапшал (Эдиб-ус-Султан) ― учитель Валиахда Мохаммед-Али, генерал-адъютант Мохаммед-Али-шаха // Восток. 2007, № 5. С. 64-78
- Прохоров Д.А., Кизилов М.Б. Шапшал Серайя Маркович (1873-1961) // Крым в лицах и биографиях. Симферополь, 2008. С. 396-400