Walter Frank Raphael Weldon FRS (15 March 1860 – 13 April 1906), was an English evolutionary biologist and a founder of biometry.

In 1881 he gained a first-class honours degree in the Natural Science Tripos; in the autumn he left for the Naples Zoological Station to begin the first of his studies on marine biological organisms.

Weldon's work was centred on the development of a fuller understanding of marine biological phenomena and selective death rates of these organisms.

Royal Society records show his election supporters included the great zoologists of the day: Huxley, Lankester, Poulton, Newton, Flower, Romanes and others.

[9] By 1893 a Royal Society Committee included Weldon, Galton and Karl Pearson 'For the Purpose of conducting Statistical Enquiry into the Variability of Organisms'.

[12] He collected the data in part, 'to judge whether the differences between a series of group frequencies and a theoretical law, taken as a whole, were or were not more than might be attributed to the chance fluctuations of random sampling.'