Seiyū (声優) is the Japanese word for voice actor.
Seiyu may also refer to:
- Seiyu Group, a Japanese group of supermarkets, shopping centers and department stores.
- Rikken Seiyūkai, known simply as Seiyūkai, a Japanese political party during the pre-war Empire of Japan.
- Seiyūhontō (True Seiyū Party), a Japanese political party during the pre-war Empire of Japan that broke away from the Rikken Seiyūkai.