Siwan

Siwan may refer to
 * Sivan, a month of the Hebrew calendar
 * The Welsh form of Joan (first name)
 * Siwan or Joan, Lady of Wales, the wife and consort of Llywelyn the Great, Prince of Wales
 * Siwan (play), by Saunders Lewis
 * Sewant, beads used as a currency by Native Americans
 * Siwan (album), a musical orchestra project by Jon Balke, and featuring Amina Alaoui
 * Siwan, Henan, a town in Xichuan County, Henan, China

India

 * Siwan district, in the state of Bihar
 * Siwan, Bihar, the headquarters of the Siwan district
 * Siwan subdivision, of Siwan district
 * Siwan (community development block), in Siwan district
 * Siwan Lok Sabha constituency, a parliamentary constituency in Bihar
 * Siwan Assembly constituency, a constituency of the Bihar Legislative Assembly
 * Siwan Junction railway station, a railway junction station in the state of Bihar
 * Siwan, Raebareli, a village in Uttar Pradesh

People

 * People with given name Siwan
 * Siwan, a Korean singer, member of boy group ZE:A
 * Siwan Morris, Welsh actress
 * Siwan Lillicrap, Welsh rugby union player