Hadyn Ellis CBE^[1] DSc (25 October 1945 – 2 November 2006)^[2] was a Welsh psychologist who was influential in the field of face processing and who had some 160 publications to his name.^[3][4]

For the largest part of his career he worked at Cardiff University, where he became pro-vice chancellor for research in 1994. He also made significant contributions to research strategy at the ESRC.

His research into face perception had significant contribution to eyewitness testimony^[5] and also the understanding of delusions of misidentification such as Capgras delusion.^[6] Ellis is also considered to be the person who coined the term cognitive neuropsychiatry.

During his career he also wrote many books, including Validation in Psychology: Research Perspectives^[7] and Perceiving and Remembering Faces.^[8]

After his death from bowel cancer, Cardiff University recognised his contribution to science and the university by naming a building in his honor.^[9] Additionally, the Hadyn Ellis Prize is awarded annually to research students at Cardiff University for the best PhD dissertation, previous winners of which have been Joseph Sweetman^[10] and Georgie Powell.^{[11][clarification needed]}