Joseph Erlanger, American physiologist and academic, Nobel Prize laureate (died 1965)

Joseph Erlanger was an American physiologist who is best known for his contributions to the field of neuroscience. Together with Herbert Spencer Gasser, he identified several varieties of nerve fiber and established the relationship between action potential velocity and fiber diameter. They were awarded the Nobel Prize in Physiology or Medicine in 1944 for these achievements.

The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, according to Alfred Nobel's 1895 will, are awarded "to those who, during the preceding year, have conferred the greatest benefit to humankind". Nobel Prizes are awarded in the fields of Physics, Medicine or Physiology, Chemistry, Literature, and Peace.

January 5 is the fifth day of the year in the Gregorian calendar; 360 days remain until the end of the year.