The Mendicant (or Begging) Orders are religious orders which depend directly on the charity of the people for their livelihood. In principle they do not own property, either individually or collectively, and have taken a vow of poverty, in order that all their time and energy could be expended on preaching the Gospel and serving the poor. Both of the two main new orders founded by Saint Dominic and Saint Francis were prompted by a concern to combat the Cathar heresy (in southern France and in northern Italy respectively) by offering a model of service to God within the community. They attracted a significant level of patronage, as much from townsfolk as aristocrats. Their focus of operation rapidly centred on towns where population growth historically outstripped the provision of parishes. Most medieval towns in Western Europe of any size came to possess houses of one or more of the major orders of friars. Some of their churches came to be built on grand scale with large spaces devoted to preaching, something of a specialism of the mendicant orders.

Saint Anthony and Saint Francis were notable inspirations to the formation of Christian mendicant traditions.

In the Middle Ages, the original mendicant orders of friars in the Church were the

• Franciscans (Friars Minor, commonly known as the Grey Friars), founded 1209
• Carmelites, (Hermits of the Blessed Virgin Mary of Carmel, commonly known as the White Friars), founded 1206–1214
• Dominicans (Order of Preachers, commonly called the Black Friars), founded 1215
• Augustinians (Hermits of St. Augustine, commonly called the austin Friars), founded 1256

The Second Council of Lyons (1274) recognized these as the four "great" mendicant orders, and suppressed certain others. The Council of Trent loosened their property restrictions. Afterwards, except for the Franciscans and their offshoot the Capuchins, members of the orders were permitted to own property collectively as do monks.

Among other orders are the

• Trinitarians (Order of the Most Blessed Trinity), founded 1193
• Mercedarians (Order of the Blessed Virgin Mary of Mercy), founded 1218
• Servites (Order of Servants of Mary), founded 1233
• Minims (Hermits of St. Francis of Paola), founded 1436
• Capuchins (Order of Friars Minor Capuchin), established 1525

The term "mendicant" may also be used to refer to other non-Catholic and non-Christian ascetics, such as Buddhist monks and Hindu holy men. The Buddhist Pali scriptures use the term bhikku for mendicant. The Buddhist mendicant tradition still survives in many Southeast Asian countries where Theravada Buddhism is practised.