c.1300, from Old French vicaire, from Latin vicarius "substitute, deputy," noun use of adj. vicarius "substituting," from vicis "change, turn, office" (see vicarious). The original notion is of "earthly representative of God or Christ;" but also used in sense of "person acting as parish priest in place of a real parson" (early 14c.).
The original Vicar of Bray (in figurative use from 1660s) seems to have been Simon Allen, who held the benefice from c.1540 to 1588, thus serving from the time of Henry VIII to Elizabeth, and was twice a Catholic and twice a Protestant, but always vicar of Bray. The village is near Maidenhead in Berkshire.