Josiah Kirby "Joe" Lilly Jr. was a businessman and industrialist who served as president and chairman of the board (1953–66) of Eli Lilly and Company, the pharmaceutical firm his grandfather, Colonel Eli Lilly, founded in Indianapolis in 1876. Lilly, the younger son and namesake of Josiah K. Lilly Sr., graduated from the University of Michigan's School of Pharmacy in 1914 where he was a member of the Chi Psi Fraternity. He served in the U.S. Army in France during World War I. At Eli Lilly and Company, where his primary focus was marketing and human resources, he served as vice president of marketing, executive vice president of the company, and president of Eli Lilly International Corporation, before succeeded his older brother, Eli Jr., as company president in 1948 and as chairman of the board in 1953.

Eli Lilly, sometimes referred to as Eli Lilly Jr. to distinguish him from his grandfather of the same name, was an American pharmaceutical industrialist and philanthropist from Indianapolis, Indiana, United States. During his tenure as head of Eli Lilly and Company, which was founded by his grandfather, the company grew from a successful, family-owned business into a modern corporation and industry leader. Lilly served as the company president (1932–1948), chairman of the board of directors, and honorary chairman of the board.