**David Conlon** (born 1982) is an Irish mathematician. He represented Ireland in the International Mathematical Olympiad in 1998 and 1999. He was an undergraduate in Trinity College Dublin winning a scholarship in 2001 and graduated in 2003. He earned a Ph.D. from Cambridge University in 2009. He is a fellow of Wadham College, Oxford and a lecturer in the department of mathematics at the University of Oxford. His research interests are in Hungarian-style combinatorics, particularly Ramsey theory, extremal graph theory, combinatorial number theory, and probabilistic methods in combinatorics.

Conlon has worked in Ramsey theory. In particular, he proved the first superpolynomial improvement on the Erdős–Szekeres bound on diagonal Ramsey numbers.

He won the European Prize in Combinatorics in 2011, for his work in Ramsey theory and for his progress on Sidorenko's conjecture that, for any bipartite graph *H*, random bipartite graphs have the fewest subgraphs isomorphic to *H*.