David Thoreson Lykken (June 18, 1928 – September 15, 2006) was a behavioral geneticist and Professor Emeritus of Psychology and Psychiatry at the University of Minnesota.

He remained on Minnesota's permanent faculty for his entire career and taught as a visiting professor at Deep Springs College.

[3] His research findings suggest that variation in baseline levels of cheerfulness, contentment, and psychological satisfaction is largely a matter of heredity.

He frequently testified as an expert witness on polygraph testing and personality assessment in the wake of Daubert standard requirements.

[9][10] Lykken defended his acceptance of money from the fund, writing "If you can find me some rich villains that want to contribute to my research—Qaddafi, the Mafia, whoever—the worse they are, the better I'll like it.