Sierra Kay Kusterbeck, better known as Sierra Kay, is an American singer-songwriter and model. She rose to prominence as the lead vocalist of the rock band VersaEmerge.

Versa was an American rock duo formed in Port St. Lucie, Florida, in 2006, as VersaEmerge. The group consisted of Blake Harnage and Sierra Kay. They had a revolving line-up, their most prolific being with bassist Devin Ingelido, who was a member from 2007 until 2011.