Heiðr
The general assumption is that here , "Heiðr" is an alternate name for the witch Gullveig , mentioned in the previous stanza , who , in turn , is often thought to be a hypostasis of Freyja . But it is sometimes argued that the "völva" who recites the poem refers to herself . 
<triplet> Heiðr <subj> Gullveig <obj> said to be the same as