Some of the earliest Green Men have been traced to ancient Rome. In pre-Christian religions, trees were held sacred, forest groves were perceived as the dwelling place of gods, goddesses, and a wide variety of nature spirits. Some scholars believe Bacchus or Dionysus to be the Green Man of the Greco-Roman period. Known widely as a god of ecstasy and divine rapture, he was also the god of vegetation.

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. Gawain had a green helmet, green armor, green shield... even a green horse. When he was decapitated, he continued to live.

Given the church's condemnation of the old pagan gods, the last place you'd expect to find Green Man is within the Christian places of worship. Nevertheless his face appears again and again. This may be the church's attempt to "make safe" those elements of paganism it failed to stamp out. The motif of rebirth clearly has Christian applications that provided the Green Man protective status within the cathedrals. Perhaps, also, the Green Man was a talisman to encourage new fertility and growth of the church as well as its constituents.

The Green Man has been suppressed and reinvented throughout history. He was banned during the Reformation, but appeared on 17th century memorials and is found on 18th century Scottish gravestones. In the Victorian era, The Green Man was used as an architectural motif from Ireland in the west to Russia in the east. At this time he played a major role in church restorations and as a decorative motif on street architecture.

"A Green Man is a sculpture, drawing or other representation of a face surrounded by (or made from) leaves. Branches or vines may sprout from the nose, mouth, nostrils or other parts of the face, and these shoots may bear flowers or fruit. Commonly used as a decorative architectural ornament, Green Men are frequently found on carvings in churches and other buildings (both secular and ecclesiastical). "The Green Man" is also a popular name for British public houses and various interpretations of the name appear on inn signs, which sometimes show a full figure rather than just the head.

The Green Man motif has many different faces and variations. Found in many cultures around the world, the Green Man is often related to natural vegetative deities springing up in different cultures throughout the ages. Primarily it is interpreted as a symbol of rebirth, or "renaissance", representing the cycle of growth being reborn anew each spring. Speculatively, the mythology of the Green Man developed independently in the traditions of separate ancient cultures and evolved into the wide variety of examples found throughout history." quote from Wikipedia