Siggeir
Siggeir is the king of Gautland (i.e. Götaland/Geatland, but in some translations also rendered as Gothland), in the Völsunga saga. In Skáldskaparmál he is given as a Sikling and a relative of Sigar who killed the hero Hagbard. Hversu Noregr byggðist specifies that the last Sigar was Siggeir's nephew.
Read more about Siggeir.