The term "saint" is more commonly associated with holy persons in Catholicism, but there are certainly saints in Buddhism. But because Buddhism is not centrally organized, as is Catholicism, there is no official sanctioning body to designate sainthood in the various schools of Buddhism.
But there are many sages, masters, and wonder-workers, both historical and contemporary, who are referred to as Buddhist saints. And each Buddhist tradition and country has its own set who are recognized not by an official process of canonization but through popular recognition of their attainments. What they all have shared, according to the hagiography and lore grown up around their lives, are the universal spiritual virtues of extraordinary humanity--including love, compassion, morality, generosity, and selflessness--and extraordinary "otherness"--that is, wisdom and access to a transcendental, non-dual perspective. In Buddhist terms, they are often referred to as bodhisattvas or "selfless spiritual awakeners."
The earliest example of Buddhist saints were the arhats ("liberated sages" in Pali, the language of the earliest Buddhist texts), the enlightened disciples of the Buddha who had completed their spiritual path. The tradition began with the Buddha's two principle disciples, Sariputra and Maudgalyayana, who are often represented in Buddhist art as standing on either side of the seated Buddha. Sariputra was known for his extraordinary wisdom and discernment, and Maudgalyayana was renowned for his psychic powers and abilities. In the intervening millennia, holy men and women who were masters with remarkable sagacity and powers in keeping with the first arhats, have been recognized as what we in the West would call saints.
In the later Tantric tradition of India and Tibet, beginning in the first centuries after Jesus' time and spanning a period of 1,500 years, ascetics who have come to be known as the mahasiddhas (realized and accomplished masters), lived saintly lives distinguished by magical powers. The best known lived during the Middle Ages, and have been sanctified as the 84 Mahasiddhas. What marked them, apart from their enlightenment, was that they came from wildly divergent backgrounds and social classes and used unorthodox methods to show that supreme liberation can take many and sundry forms. The adept Tandhepa, for one, started out as a compulsive gambler who lost all his money but became enlightened when he grasped the notion that the universe was as empty was his pockets.
Even today, there are teachers in the Tibetan tradition who fall into the mahasiddha category. I have had the extreme good fortune of meeting and studying with some of them, such as my late root guru, the 16th Gyalwa Karmapa, who was clairvoyant and a miracleworker, and the greatest lama I have ever met.
And then there is the 12th-century saint Milarepa, Tibet's greatest yogi, poet, and miracleworker who could reportedly fly as well as keep himself warm while wearing nothing but a cotton robe. He also reportedly turned green from decades of ascetic Himalayan cavedwelling, subsisting mainly on boiled wild nettle soup,sd which lent him his fabled hue. One of Milarepa's contemporaries was Machik Labdron, the only female founder of an extant Tibetan Buddhist practice lineage, Chod (literally "cutting," which refers to ego cutting through radical meditation practices). The two preeminent 14th-century scholar and yogi saints Longchenpa and Tsongkhapa remain among the most highly venerated Tibetan sages today. In the same category is Atisha, the 11th-century Indian abbot who brought the lojong, which means "mind training" or "attitude adjustment," techniques to Tibet, stressing the awakening of "buddha-mind" (bodhicitta) in both ethical living and contemplative life.
As I mentioned, each Buddhist tradition has its own set of saints, holy persons, and spiritual exemplars. One of the most prominent of saints in Chinese and Japanese Buddhism is the sixth-century Indian patriarch Bodhidharma, who founded the Zen or Ch'an school in China. In the 13th century, Dogen Zenji helped bring Zen from China to Japan, and widely disseminated it through his lucid, poetic teachings, writings, and with the establishment of monastic traditions; he remains that country's greatest religious personality. Others in Japan who are considered extraordinarily masterful and loving sages include Kukai (Kobo Daishi), 774-835, who was the founder of the Tantric Vajrayana "Shingon" sect and opened the first school for peasant children in Japan; Shinran, the 12th-century founder of the Japanese Pure Land (Amitabha) school; Nichirin, father of the eponymous Nichiren sect or Lotus School School in 13th-century in Japan; and Fuji-san, the living head of the Nichiren today.