John Conrad Otto (born near Woodbridge, New Jersey, 15 March 1774; died in Philadelphia, 26 June 1844) was a United States physician.

[1] His father, Bodo Otto, was a physician, and warmly attached to the patriot cause during the American Revolutionary War.

[1] He was a fellow of the College of Physicians, in which he held the office of censor, and from 1840 until his death that of vice president, and was for many years a member of the American Philosophical Society (elected 1817).

His grandfather came to this country from Germany in 1752, settled in Philadelphia, where he engaged in the practice of medicine, and during the winter of 1778 had charge of the hospital of the Continental Army at Valley Forge.

His son William Tod Otto was a judge and the eighth reporter of decisions of the United States Supreme Court.