Grete Griffin (née Šadeiko; born 29 May 1993)[1] is an Estonian heptathlete.

At the 2010 World Junior Championships in Moncton, Canada she placed fourth with her personal record 5705 points, just one point behind Helga Margrét Thorsteinsdóttir.

[2] In the fall of 2012, she joined Florida State University.

In August 2016, Šadeiko became romantically linked to NFL quarterback Robert Griffin III.

This biographical article relating to Estonian athletics is a stub.