| Semyon Zinovyevich Alapin | |
| Birth Date: | 19 November 1856 |
| Birth Place: | Saint Petersburg, Russian Empire |
| Death Place: | Heidelberg, Republic of Baden, Germany |
| Occupation: | railway engineer, grain commodities merchant |
| Known For: | Analyzing chess openings |
Semyon Zinovyevich Alapin (ru|Семён Зиновьевич Алапин; – 15 July 1923) was a Russian chess player, openings analyst, and puzzle composer. He was also a linguist, railway engineer and a grain commodities merchant.
Born in Saint Petersburg, Russia, into a Jewish family on,[1] nephew of the Jewish memoirist Pauline Wengeroff. He was one of the strongest chess players in the Russian Empire in the late 19th century. Due to the 1917 Revolution in Russia, he had to spend his final years in exile. He died in Heidelberg, Germany, on 15 July 1923.
Today he is best known for his creation of opening systems in almost all major openings. Most of these are of little significance today, but Alapin's Variation of the Sicilian Defence is an important opening line that is often played by leading grandmasters.