Julian Ernst Besag FRS (26 March 1945 – 6 August 2010) was a British statistician known chiefly for his work in spatial statistics (including its applications to epidemiology, image analysis and agricultural science), and Bayesian inference (including Markov chain Monte Carlo algorithms).

Besag was an ISI highly cited researcher; his 1986 paper "On the Statistical Analysis of Dirty Pictures" was the most cited paper by a UK mathematical scientist in the 1980s.

The Royal Statistical Society awarded him its Guy Medal in Silver in 1983 for his contributions to spatial statistics, and he was elected a Fellow of the Royal Society in 2004.

[2] For an array of random variables Yij, stochastic dependence was known to be important.

He therefore suggested using multivariate distributions for such a variable, taking inspiration from statistical physics and unpublished work by Peter Clifford and John Hammersley:[2]