Muncy Township is a township in Lycoming County, Pennsylvania. The population was 1,059 at the 2000 census. It is part of the Williamsport, Pennsylvania Metropolitan Statistical Area.

The unincorporated village of Pennsdale is located there. There is a Religious Society of Friends (Quaker) Meeting House in Pennsdale that was built in 1799, and is one of the oldest buildings and perhaps the oldest house of worship in the county.

Muncy Township is bordered by Mill Creek Township to the north, Wolf Township to the east, Muncy Creek Townsip and the West Branch Susquehanna River to the south, Fairfield Township to the west, and by Upper Fairfield Township to the northwest.

Muncy Township, named for the Munsee tribe, was the first township in the county north of the West Branch Susquehanna River to be formed (predating even Lycoming County itself). It was originally formed as a part of Northumberland County on 9 April 1772. Muncy Township, as one of the seven original townships of Northumberland County was once an immense township. It had an indefinite norther border. The southern border of the township was the West Branch Susquehanna River. The eastern boundary may have been Muncy Creek and the western boundary was, like the northern boundary, indefinite. Loyalsock Township was the first township to be formed from Muncy Township in 1786. This division encompassed the land between Loyalsock and Lycoming Creeks. The township was divided several more times. Muncy Creek Township was formed in 1797, Shrewsbury Township in 1804, Penn Township in 1828, Wolf Township in 1834 and lastly in 1878 when Mill Creek Township was formed.

Samuel Wallis was one of the first permanent settlers in Muncy Township. Known as the "Land King" Wallis operated Muncy Farms which was for its time a large and very successful farm. Wallis first came to the West Branch Susquehanna Valley in 1768 as a surveyor. He was born in Harford County, Maryland in 1730 to a wealthy Quaker family. Wallis received a good education and inherited a large fortune. He sought to expand his fortune in various ways. He worked for a while as a shipping merchant in Philadelphia and became a surveyor. While working as a surveyor Wallis was introduced to what would become his home in 1768. He gave up his job as a surveyor and began acquiring land up and down the West Branch Valley. His holdings are said to have extended as far west as Pine Creek from his base of operations in Muncy Township. Wallis held title to the land that has since become, Muncy, Muncy Creek Township, Muncy Township, Montoursville, Loyalsock Township, Williamsport, Woodward Township, Piatt Township, Porter Township and Jersey Shore. Wallis' home was one of, if not the, first houses to be built in what is now Lycoming County. Samuel Wallis was such an important figure in the early history of Muncy Township that Fort Muncy was built on his land. This fort served as an outpost for the colonial army of Pennsylvania providing a safe haven for settlers from various Indian attacks.

Samuel Wallis married Lydia Hollingsworth in Philadelphia on 1 March 1770. They settled at Muncy Farms soon after the marriage and continued to farm while Wallis continued to expand his land holdings. Wallis was forced to flee Muncy Farms during the "Big Runaway." During the American Revolutionary War, settlements throughout the Susquehanna valley were attacked by Loyalists and Native Americans allied with the British. After the Wyoming Valley battle and massacre in the summer of 1778 (near what is now Wilkes-Barre) and smaller local attacks, the Big Runaway occurred throughout the West Branch Susquehanna valley. Settlers fled feared and actual attacks by the British and their allies. Homes and fields were abandoned, with livestock driven along and a few possessions floated on rafts on the river east to Muncy, then further south to Sunbury. The abandoned property was burnt by the attackers. Some settlers soon returned, only to flee again in the summer of 1779 in the "Little Runaway." Sullivan's Expedition helped stabilize the area and encouraged resettlement, which continued after the war. Wallis returned as soon as it was safe and continued to farm. He also built a gristmill along Carpenter's Run. The construction of this mill was entrusted to Colonel Henry Antes of Nippenose Township. Antes was the operator of the most successful mill in the area along Antes Creek.

Samuel Wallis and James Wilson a signer of the Declaration of Independence and the Supreme Court appointee of George Washington became involved with Theophilus Cazenove and the Holland Land Company. This company bought up much of the land that his now northwestern Pennsylvania and western New York near the Great Lakes. Wallis worked as a surveyor and assessor for the land company and Wilson was heavily invested in the operation. Wilson owed a tremendous debt to Wallis and others. He fled to Edenton, North Carolina to escape his debts. Wallis followed him there in an effort to reach a settlement. They reached a prelimary agreement and agreed to meet again. Both men died before the debts could be settled. Wallis contracted yellow fever on his return from North Carolina and died in Philadelphia on 14 October 1798. Wilson died in Edenton, North Carolina on 21 August 1798. Wallis' heir were unable to collect Wilson's debt. Wallis himself left a large debt behind. The heirs were forced to sell Samuel Wallis' land for a fraction of his value to Henry Drinker. Drinker gave the land to his daughter and son-in-law, Elizabeth and Charles Hall. Muncy Farms became known as Hall's Farms.

Pennsdale is a village in Muncy Township. It was founded by a group of Quakers in 1799. They built a meetinghouse there. The first meetings were held in Samuel Wallis's home as early as 1791. The Quakers continue to hold meetings in Pennsdale.