Buddhism

Buddhism was an Earth religion whose adherents followed the teachings of Buddha.

Among the prizes that the Doctor obtained during a game of backgammon against Kublai Khan in the 13th century was the sacred tooth of Buddha which Marco Polo had brought from India. (DW: Marco Polo)

The monks at the Det-Sen Monastery in Tibet were Buddhist. (DW: The Abominable Snowmen)

K'anpo Rimpoche became the abbot of a Buddhist meditation centre in England. (DW: Planet of the Spiders)

As a result of his experiences in UNIT, Brigadier Lethbridge-Stewart adopted Zen Buddhist practices. These helped him resist Vardan mind control as well as giving him a new perspective upon the Doctor and his role in the cosmic order (that is, as a Bodhisattva of Justice and Compassion). (NA: No Future, EDA: The Shadows of Avalon)