Nameisis or Namejs (also Nameise, Nameyxe) was a Semigallian duke in the second half of the 13th century. He ruled in the western part of Semigallia, with his capital at Tērvete (present-day Latvia). In 1279–81, he led a Semigallian uprising against the Livonian Order, a crusading military order. Very little is known about his life. He is mentioned only in the Livonian Rhymed Chronicle and in some documents from the 14th century. For this reason he is sometimes referred as semi legendary ruler in Latvian historiography.