The Ghergher beast is a giant creature from Yaderan folklore.

The Yaderan girl Taya once told Odo a story about the Ghergher beast:

"The Great Minra said to the evil changeling, "Well maybe you can turn into a mountain, or a Ghergher Beast, or a tornado... those are big things and big things are easy... but I bet you can't turn into something small...like a loaf of greenbread." And so the changeling said "Yes I can." and he did... and then the Great Minra gobbled him up." (DS9: "Shadowplay")