Peter Ludlow (born January 16, 1957), who also writes under the pseudonym Urizenus Sklar, is currently a professor of philosophy at Northwestern University although he has just accepted a position at Rutgers University's Center for Cognitive Science (RUCCS). Before moving to Northwestern, Ludlow taught at University of Toronto, the University of Michigan, and the State University of New York at Stony Brook. He has done much interdisciplinary work on the interface of linguistics and philosophy—in particular on the philosophical foundations of Noam Chomsky's theory of generative linguistics and on the foundations of the theory of meaning in linguistic semantics. He has worked on the application of analytic philosophy of language to topics in epistemology, metaphysics, and logic, among other areas.

Ludlow has also established a research program outside of philosophy and linguistics. Here, his research areas include conceptual issues in cyberspace, particularly questions about cyber-rights and the emergence of laws and governance structures in and for virtual communities, including online games. In recent years Ludlow has written nonacademic essays on hacktivist culture and related phenomena such as Wikileaks.

Ludlow received his PhD in philosophy from Columbia University in 1985 under the direction of Charles Parsons, but also studied with Noam Chomsky and James Higginbotham at MIT. He received his B.A. in 1979 from Bethel College.