Besides Legolas, how many children does King Thranduil have?
According to all the Tolkien literature, appendices, and letters, Thranduil had no other children named besides Legolas. BUT: Tolkien never states emphatically that Legolas was Thranduil’s ‘only’ child. So theoretically Thranduil may have had other children. Please be aware that any brothers or sisters of Legolas that you may have read about were created by the fan fic writers, and not by JRR Tolkien. I have nothing against Legolas having brothers and sisters.