David Baltimore, a towering figure in molecular biology and a Nobel laureate, has passed away at age 87. Renowned for his discovery of reverse transcriptase—a key enzyme in the replication of retroviruses—Baltimore’s groundbreaking work revolutionized the understanding of cancer and viral diseases. His contributions challenged fundamental biological dogma, influencing perspectives on gene expression and viral oncogenesis. Having started his independent career at the Salk Institute in 1965, Baltimore’s legacy spans decades of pioneering research and mentorship that shaped the biotech and biomedical landscape.