Green Man

To add on to what Kim said, I found some more information on the Green Man and how he relates to SGGK:
"The Green Man is often perceived as an ancient Celtic symbol. In Celtic mythology, he is a god of spring and summer. He disappears and returns year after year, century after century, enacting themes of death and resurrection, the ebb and flow of life and creativity. The Arthurian legend of Sir Gawain, The Green Knight, is a notable image of the Green Man from the Middle Ages. The green knight had a green helmet, green armor, green shield... even a green horse. When he was decapitated, he continued to live." http://www.dl.ket.org/humanities/connections/class/medren/greenman.htm