Mellis is a small village in Suffolk, England. It has the largest area of unfenced common land in England. Oliver Cromwell exercised his troops in Mellis. It once had a railway station on the main line between London and Norwich, and a small branch line that ran to nearby Eye.
Mellis Common is a 59 hectare nature reserve. In summer rare plants such as green-winged orchid, sulphur clover and adder's tongue fern flourish. The abundance of small mammals also makes the site a favourite hunting ground for barn owl and tawny owl.
The 14th-century parish church of St Mary, restored in 1859 and 1900, is a Grade II* listed building.
In 1968, Roger Deakin (1943 – 2006), writer and environmentalist, bought Walnut Tree Farm on the edge of Mellis Common, which he rebuilt over many years and where he lived until his death.