Gwennap (Standard Written Form: Lannwenep (village), Pluw Wenep (parish)) is a village and civil parish in Cornwall, England, United Kingdom. It is about five miles (8 km) southeast of Redruth. Hamlets of Burncoose, Comford, Coombe, Crofthandy, Cusgarne, Fernsplatt, Frogpool, Hick's Mill, Tresamble and United Downs lie in the parish, as does Little Beside country house.

In the 18th and early 19th centuries Gwennap parish was the richest copper mining district in Cornwall, and was called the "richest square mile in the Old World". According to one estimate the mines of Gwennap produced tin and copper to the value of £10 million in the 19th century. It is near the course of the Great County Adit which was constructed to drain mines in the area including several of the local once-famous mines such as Consolidated Mines, Poldice mine and Wheal Busy. Today it forms part of area A6i (the Gwennap Mining District) of the Cornwall and West Devon Mining Landscape World Heritage Site.

It lends its name to Gwennap Pit, where John Wesley preached on 18 occasions between 1762 and 1789, although Gwennap Pit is about 1.7 miles (2.7 km) to the northwest, at the hamlet of Busveal near St Day. The pit was caused by mining subsidence in the mid-18th century. After Wesley's death the local people turned the pit into a regular circular shape with turf seats. The location of the pit has been described as being used for Cornish wrestling tournaments prior to its transformation.

Gwennap church is dedicated to St Wenappa; in 1225 it was given to the chapter of Exeter by Lord William Briwere. The parish church is an old foundation, but was rebuilt in the 15th century because of population growth caused by mining and then thoroughly restored in the 19th century. The tower is detached. In 1882, following the removal of the centre gallery, which was said to be an eyesore, The Cornishman newspaper described the church as one of the prettiest in Cornwall. It was later described by Charles Henderson, as "few Cornish churches are less interesting than Gwennap".

There is a Cornish cross in the churchyard which was moved to the vicarage garden in the 1840s from Chapel Moor. It has a crude crucifixus figure and a small Latin cross on the front and a large Latin cross on the back and is probably a fragment of a larger cross. There is also an ornamented cross shaft which was found in the church wall about 1860 and by mistake used again in the vestry foundations.

On 6 September 1762 John Wesley came to Gwennap and attracted a great crowd of tin miners. Unfortunately the day was very windy and Wesley could not make himself heard. Someone suggested the shelter of Gwennap Pit, about 1.5 miles away, so the whole crowd walked there and Wesley was able to preach his sermon. Wesley's Journal records, "The wind was so high that I could not stand at the usual place at the village of Gwennap; but a small distance was a hollow capable of containing many thousands of people. I stood on one side of this amphitheatre towards the top and with people beneath on all sides, I enlarged on those words in the gospel for the day, 'Blessed are the eyes which see the things that ye see....hear the things that ye hear.'"

He continued to use the Pit for a total of 18 times; it is claimed that in 1773 he attracted a staggering 32,000 people. (Normally the pit provides comfortable seating for 2,000.) His final visit was in 1789.

Mining in Gwennap is an industry stretching back to prehistoric times when tin streaming in the Carnon Valley is believed to have occurred. In surrounding valleys stones of cassiterite (SnO₂) were washed downstream from outcropping lodes and trapped in the alluvial mud where they could be easily extracted. Later these outcropping tin lodes were worked by 'bounders' and the open workings (coffins) of these early miners are still partially visible at Penstruthal.