Þrymlur is an Icelandic mythological rímur cycle dated to the 15th century.
Þrymlur narrates Thor's reclaiming of his hammer Mjöllnir from the giant Þrymr, a myth also preserved in the Eddic poem Þrymskviða. The version in Þrymlur is believed to be based on that of Þrymskviða, but is in some respects more detailed and has some independent elements.
The cycle consists of three rímur, each in a different verse form. The first is in ferskeytt, the second in braghent and the third in stafhent. The rímur are only preserved in one medieval manuscript, Staðarhólsbók. The beginning of the first ríma is lost.
Sophus Bugge argued that the Scandinavian folk song Torsvisen was originally based on Þrymlur, pointing out some parallels. Finnur Jónsson and Björn Karel Þórólfsson regarded this as highly improbable.