Fritz Joseph Ursell FRS[1] (28 April 1923 – 11 May 2012) was a British mathematician noted for his contributions to fluid mechanics, especially in the area of wave-structure interactions.

[6] He held the Beyer Chair of Applied Mathematics at the University of Manchester from 1961 to 1990,[7] was elected Fellow of the Royal Society in 1972 and retired in 1990.

At the end of 1943 Ursell joined the Admiralty as a part of a team—headed by George Deacon —whose task was to formulate rules for forecasting waves for the allied landings in Japan.

In 1957 he spent a year at Massachusetts Institute of Technology, having been invited by Arthur Ippen.

[11] In 1957 he published together with Clive R. Chester and Bernard Friedman a classic paper that introduced a method to find asymptotic expansions for contour integrals with coalescing saddle points.