Leioproctus, the hairy colletid bee, is a genus in the plaster bee family Colletidae. Its members are primarily found in Australasia and temperate South America, and include the most common native bees in New Zealand.

The Colletidae are a family of bees, and are often referred to collectively as plasterer bees or polyester bees, due to the method of smoothing the walls of their nest cells with secretions applied with their mouthparts; these secretions dry into a cellophane-like lining. The five subfamilies, 54 genera, and over 2000 species are all evidently solitary, though many nest in aggregations. Two of the subfamilies, Euryglossinae and Hylaeinae, lack the external pollen-carrying apparatus that otherwise characterizes most bees, and instead carry the pollen in their crops. These groups, and most genera in this family, have liquid or semiliquid pollen masses on which the larvae develop.