Philip Peter Ross Nichols (1902–1975) was a British academic, poet, artist, and historian who significantly contributed to the revival of modern Druidry. He established the Order of Bards, Ovates and Druids in 1964, aiming to revitalize Druidic practices with a focus on Celtic mythology, bardic arts, and seasonal celebrations. Nichols's work also touched upon broader philosophical and social concerns, including pacifism and monetary reform.

Nichols's engagement with Druidism involved reforming existing Druidic traditions. He was a Member and Chairman of the Druid Order, though he introduced significant changes to its practices, incorporating a greater emphasis on Celtic lore and a structured three-grade system. His influential book, 'The Book of Druidry,' published posthumously, further shaped the understanding and practice of Druidism. He also had a notable career in publishing and editing, contributing to and editing works related to occultism and magic.

In 1964, Ross Nichols founded the Order of Bards, Ovates and Druids, an organization dedicated to the study and practice of Druidry. This initiative aimed to revive and modernize ancient Druidic traditions, incorporating elements of Celtic mythology and spirituality. Nichols, who also went by the druidic name Nuinn, structured the Order's teachings into three distinct grades, drawing inspiration from classical accounts of Druidic divisions. His efforts were instrumental in reintroducing Druidism to a wider audience in the 20th century, fostering a renewed interest in Celtic neopaganism.

Nichols played a crucial role in revitalizing interest in Celtic neopaganism and Druidry during the 20th century. He was actively involved with the Druid Order, a group with a claimed lineage dating back to 1717, though historical analysis suggests its modern form emerged later. Nichols's personal contributions focused on enriching modern Druidry with a deeper appreciation for Celtic mythology and the practice of Bardcraft. He also advocated for the observance of the eight seasonal festivals and developed a graded system of teachings, significantly shaping the contemporary practice of Druidry.

Beyond his work in Druidry, Ross Nichols was a published poet, artist, and historian. His academic background at Cambridge influenced him with thinkers like James George Frazer, Sigmund Freud, and Carl Jung. During his life, he engaged with journalism, teaching, and social work, developing strong socialist and pacifist convictions and supporting C. H. Douglas's Social Credit theories for monetary reform. Nichols was also a vegetarian and an early member of the naturist community in Britain. His literary output includes poetry collections and significant editorial work on occult and magical texts, such as Gerald Gardner's 'Witchcraft Today.'