In Norse mythology, Leikn is a giantess killed by Thor.
The fact is mentioned in a lausavísa composed by Vetrliði Sumarliðason which praises Thor for having killed giants and giantesses:
Leggi brauzt Leiknar,
stétt of Gjǫlp dauða.
—Edith Marold's edition
You broke Leikn's bones,
you pounded Thrivaldi
you cast down Starkad,
you stood over the dead Gialp.
—Skáldskaparmál, Faulkes' translation
Leikn's name was used by skalds in kennings. Hallfreðr vandræðaskáld thus uses the kenning "Leikn's horse" (hestr Leiknar) for a wolf (Óláfsdrápa, 6) and Hallvarðr háreksblesi calls the raven "hawk of Leikn of points" (haukr Leiknar odda) that is "hawk of valkyrie" (Knútsdrápa, 6).
Leikn is also listed in the þulur.