Venango County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 50,454. Its county seat is Franklin. The county was created in 1800 and later organized in 1805. The county is part of the Northwest Pennsylvania region of the state.

Venango County comprises the Oil City, PA micropolitan statistical area. It is part of the Pittsburgh and Erie media markets (with Erie channels available to Comcast subscribers in the area).

Venango County was created on March 12, 1800, from parts of Allegheny and Lycoming Counties. The name "Venango" is derived from the Native American name of the region, Onenge, meaning Otter. This was corrupted in English as the Venango River. The settlement at its mouth was likewise called Venango, which since March 3, 1871, has been the South Side of Oil City. Venango County was home to an oil boom in the years following discovery of natural oil (petroleum) in the mid-1850s.

George Bissell, a Yale University chemistry professor, and Edwin L. Drake, a former railroad conductor, made the first successful use of a drilling rig on August 28, 1859, near Titusville. (Although Titusville is in Crawford County, the first oil well was drilled outside of town, less than a mile inside of the Venango County boundary) This single well soon exceeded the entire cumulative oil output of Europe since the 1650s. Within weeks, oil derricks were erected all over the area. Other oil boom towns located in Venango County included Franklin, Oil City, and the now defunct Pithole City. The principal product of the oil was kerosene.

McClintocksville was a small community in Cornplanter Township in Venango County. In 1861, it was the location of Wamsutta Oil Refinery, the first business venture of Henry Huttleston Rogers, who became a leading United States capitalist, businessman, industrialist, financier, and philanthropist. Rogers and his young wife Abbie Palmer Gifford Rogers lived in a one-room shack there along Oil Creek for several years beginning in 1862.

After joining Standard Oil, Rogers invested heavily in various industries, including copper, steel, mining, and railways. The Virginian Railway is widely considered his final life's achievement. Rogers amassed a great fortune, estimated at over $100 million, and became one of the wealthiest men in the United States. He was also a generous philanthropist, providing many public works for his hometown of Fairhaven, Massachusetts, and financially assisting helping such notables as Mark Twain, Helen Keller, and Dr. Booker T. Washington.

A little girl named Ida M. Tarbell, whose father was an independent producer whose small business was ruined by the South Improvement Company scheme of 1871 and the conglomerate which became Standard Oil. Introduced to each other in 1902 by their mutual friend Twain, Tarbell, who had become an investigative journalist and Rogers, who knew of her work, shared meetings and information over a two-year period which led to her epoch work, The History of the Standard Oil Company, published in 1904, which many historians feel helped fuel public sentiment against the giant company and helped lead to the court-ordered break-up of it in 1911.

The oil heritage of Venango County is commemorated by a Pennsylvania State Park and many heritage sites which help tell the story and memorialize the people of the oil boom of the late 19th and early 20th centuries.