(October 29, 1849 – March 29, 1913) was an American medical doctor and anatomist known for his anatomical drawings.

[1] He attended the University of Pennsylvania for undergraduate study, beginning in 1865; however, in 1868 he left the University of Pennsylvania during his senior year in order to begin medical school at Jefferson Medical College.

[1] During medical school, McClellan was a clinical assistant to Joseph Pancoast and Samuel D.

[1] His was widely known for his medical work Regional Anatomy in Its Relation to Medicine and Surgery in which McClellan made his own photographs from his own dissections and completed the illustrations himself.

His anatomical expertise was recognized by Jefferson Medical College in his 1906 appointment as chair of the applied anatomy department.