In 1885 a young pharmacist called Charles Alderton was working and serving carbonated soft drinks at Morrison's Old Corner Drug Store, in Waco, Texas. A Dr. Charles Pepper owned the shop and the young pharmacist was engaged to his daughter. Having noted that customers soon tired of drinking the same old fruit flavors, the inventive Alderton decided to make something new by blending several fruit extracts.
After numerous experiments, he finally created one he liked, which he named Dr. Pepper after his employer and prospective father-in-law. (Source The Encyclopedia of Trivia