Presents an obituary for Arthur R. Jensen. Arthur R. Jensen epitomized the "London School" of psychological thought, studying human individuality as a branch of biology by teaming evolutionary, genetic, and experimental/multivariate/quantitative methods to examine psychological diversity. His intellectual ancestry traces back through his mentor Hans Eysenck to Cyril Burt, Charles Spearman, and, ultimately, Sir Francis Galton. Haggbloom et al. (2002, Review of General Psychology) ranked him among the top 50 eminent psychologists of the 20th century primarily for his work on the construct of general intelligence (g) and its antecedents. But he was also known for his studies in human learning, memory, the cumulative deficit hypothesis, Spearman's hypothesis, the speed of information hypothesis, and test bias. Yet, because of the controversial nature of his work, his career was conspicuously marked by tensions: The extent to which his work was either admired or reviled by many distinguished scientists is unparalleled.