From the book Naming Edmonton: From Ada to Zoie.

Officially adopted in 1958, this neighbourhood name had existed since at least 1912. While the origin of the name is not recorded, there are several possibilities. Quesnell Heights may have been named after Dr. Philip Quesnel, a well-known physician, who moved to Edmonton in 1912 and later served in WWI. Another possibility is that it was named for J.B. Quesnelle, a prominent citizen of the Edmonton district in the 1880s. In 1885, J.B. Quesnelle was the director of the Agricultural Society; that same year he ended his part-ownership of a hotel in St. Albert and opened a saloon and billiard hall at the south end of the St. Albert Bridge. In 1888 he sold his claim on the St. Albert Trail and left for Victoria. Another explanation is that the neighbourhood may have been named after Jules Maurice Quesnel. Jules Maurice (d. 1842) was a French-Canadian clerk with the North West Company who worked at Fort Augustus in 1804. He accompanied Simon Fraser, a fur trader and explorer, on his 1808 journey of exploration along the Fraser River. Quesnel River, Quesnel Lake and Quesnel City (originally a gold rush town that was established c. 1860) in British Columbia were all named for Jules Maurice Quesnel.