Peter David Mosses (born 1948) is a British computer scientist. Peter Mosses studied mathematics as an undergraduate at Trinity College, Oxford, and went on to undertake a DPhil supervised by Christopher Strachey in the Programming Research Group while at Wolfson College, Oxford in the early 1970s. He was the last student to submit his thesis under Strachey before Strachey's death. In 1978, Mosses published his compiler-compiler, the Semantic Implementation System (SIS), which uses a denotational semantics description of the input language.