J.M.E. McTaggart was a British philosopher known for his work in metaphysics and the philosophy of time. He is best recognized for his argument against the existence of time, which he presented in his famous essay, "The Unreality of Time." McTaggart proposed that time is an illusion, arguing that our perception of past, present, and future is fundamentally flawed. His ideas sparked significant debate among philosophers, influencing thinkers like Bertrand Russell and Martin Heidegger. McTaggart's distinction between the A-series and B-series of time has become a crucial part of discussions in the philosophy of time, shaping how we understand temporal concepts today.