A surplice (/ˈsɜːrplɪs/; Late Latin superpelliceum, from super, "over" and pellicia, "fur garment") is a liturgical vestment of Western Christianity. The surplice is in the form of a tunic of white linen or cotton fabric, reaching to the knees, with wide or moderately wide sleeves.

It was originally a long garment with open sleeves reaching nearly to the ground. As it remains in the Western Christian traditions, the surplice often has shorter, closed sleeves and square shoulders. Anglicans typically refer to a Roman-style surplice with the Medieval Latin term cotta (meaning "cut-off' in Italian), as it is derived from the cut-off alb. Some English-speaking Catholics may not make the distinction between the two styles and refer to both as a "surplice".

It seems most probable that the surplice first appeared in France or England, from whence its use gradually spread to Italy [citation needed]. It is possible that there is a connection between the surplice and the Gallican or Celtic alb, an ungirdled liturgical tunic of the old Gallican Rite, which was superseded during the Carolingian era by the Roman Rite. The founding of the Augustinian Canons in the second half of the eleventh century may have had a special influence upon the spread of the surplice. Among the Augustinian Canons the surplice was not only the choir vestment, but also a part of the habit of the order.

The surplice originally reached to the feet, but as early as the 13th century it began to shorten, though as late as the 15th century it still fell to the middle of the shin, and only in the 17th and 18th centuries in Continental Europe did it become considerably shorter. In several localities it underwent more drastic modifications in the course of time, which led to the appearance of various subsidiary forms alongside the original type. For example:

The first two of these forms developed very early; and, in spite of their prohibition by synods here and there (for example that of Liège circa 1287), they survive in various places to the present day. The latter two only appeared after the close of the Middle Ages: the first of them in South Germany, the second more especially in Venetia, where numerous pictorial records attest its use. As a rule, however, only the lower clergy wore these subsidiary forms of surplice. They came about partly under the influence of secular fashions, but more particularly for convenience.

Lack of exact information obscures the older history of the surplice. Its name derives, as Durandus and Gerland also affirm, from the fact that its wearers formerly put it on over the fur garments formerly worn in church during divine service as a protection against the cold. The word derived its name from the Medieval Latin word superpellicium which divides into super, "over", and pellicia, "fur garment".

Some scholars trace the use of the surplice at least as far back as the 5th century, citing the evidence of the garments worn by the two clerics in attendance on Bishop Maximian represented in the mosaics of the Basilica of San Vitale at Ravenna; in this case, however, confusing the dalmatic with the surplice.

In all probability the surplice forms no more than an expansion of the ordinary liturgical alb, due to the necessity for wearing it over thick furs. The first documents to mention the surplice date from the 11th century: a canon of the Synod of Coyaca in Spain (1050); and an ordinance of King Edward the Confessor. Rome knew the surplice at least as early as the 12th century. It probably originated outside Rome, and was imported thence into the Roman use. Originally only a choir vestment and peculiar to the lower clergy, it gradually—certainly no later than the 13th century—replaced the alb as the vestment proper to the administering of the sacraments and other sacerdotal functions.