The Sakai clan was a Japanese samurai clan that claimed descent from the Nitta branch of the Minamoto clan, who were in turn descendants of Emperor Seiwa. Serata (Nitta) Arichika, a samurai of the 14th century, was the common ancestor of both the Sakai clan and the Matsudaira clan, which the Sakai later served. In the Sengoku period, under Tokugawa Ieyasu, the Sakai became chief retainers. In the Edo period, because of their longstanding service to the Tokugawa clan, the Sakai were classified as a fudai family, in contrast with the tozama.

This is a list of Japanese clans. The old clans (gōzoku) mentioned in the Nihon Shoki and Kojiki lost their political power before the Heian period, during which new aristocracies and families, kuge, emerged in their place. After the Heian period, the samurai warrior clans gradually increased in importance and power until they came to dominate the country after the founding of the first shogunate.