Portland Bill is a narrow promontory (or bill) of Portland stone, which forms the most southerly part of Isle of Portland, and therefore also the county of Dorset, England.

The Bill is an important way-point for coastal traffic, and so three lighthouses have been built to protect shipping, in particular from its strong tidal race and shallow reef.

The most recent lighthouse is the distinctively white and red striped Portland Bill Lighthouse, which was built in 1906 and is 35 metres (115 ft) high. Tours of the lighthouse are operated by Trinity House

Nearby Pulpit Rock was formed due to quarrying, and is a popular tourist attraction, as is the lighthouse.