Sigvatr Þórðarson (Sighvatr Þórðarson, Sigvat Tordarson) or Sigvat the Skald (995-1045) was an Icelandic skald. He was a court poet to King Olaf II of Norway, as well as Canute the Great, Magnus the Good and Anund Jacob, by whose reigns his floruit can be dated to the earlier eleventh century.
Sigvatr was the best known of the court skalds of King Olaf and also served as his marshal (stallare). Most of his poems were texts that praised King Olaf. Many of the poems from St. Olaf's saga in Heimskringla are by Sigvatr. Víkingarvísur is the oldest of the surviving long poems attributed to him. The poem tallies King Olaf’s battles on his Viking expeditions until 1015, when he returned to Norway to carve out a kingdom for himself.
In Nesjavísur, the next oldest poem by Sigvatr, the skald describes the naval battle between Olaf and Sveinn Hákonarson at the Battle of Nesjar outside Brunlanes in 1016, the key moment in Olaf's ascent to power in Norway 
Approximately 160 verses of Sigvatr's poetry have been preserved, more than any for other poet from this period. The style of Sigvat's poems is simpler and clearer than that which generally characterises older compositions. Although his verse is still dense, he uses fewer complex poetic circumlocutions than many of his predecessors, and as a Christian poet, he by and large avoids allusions to pagan mythology.
- Víkingarvísur, composed c. 1014-15. On the early deeds of king Olaf
- Nesjavísur. On the battle of Nesjar
- Austrfararvísur. On a journey to Sweden
- Drápa um Óláf Konung.
- Vestrfararvísur ("Western travel verses"). On a journey to Britain
- Kvæði um Erling Skjalgsson. On Erlingr Skjalgsson
- Flokkr um Erling Skjalgsson. On Erlingr Skjalgsson
- Kvæði um Ástríði Dróttningu. Poem about Queen Ástríðr.
- Knútsdrápa. In memory of King Knút
- Bersöglisvísur. A reprimand to king Magnus
- Erfidrápa Óláfs helga. In memory of king Olaf
- Lausavísur ("The lausavísur").
- Brot. Fragments.
- Sturlason, Snorre (2004). Heimskringla or the Lives of the Norse Kings. Kessinger Publishing. p. 225. ISBN 0-7661-8693-8.
- Fell, Christine, 1981: Víkingarvísur. In: Speculum Norroenum. Norse Studies in Memory of Gabriel Turville Petre. Ed. U. Dronke. Odense. Pp. 106–22
- Sigvat Tordarson (Store norske leksikon)
- Sigvat Tordsson – utdypning (Store norske leksikon)