Pater Noster lighthouse, Maritime navigational aid in Tjörn Municipality, Sweden

Pater Noster lighthouse is a red cast-iron tower on Hamneskär, its lower two-thirds an open lattice of vertical and diagonal struts crossed by horizontal rings, rising from a low grey stone and concrete base. Above the framework sits a solid cylindrical section, then a glazed lantern room with a domed roof and a narrow railed gallery. A small red wooden building with a pitched roof and chimney stands beside it.

Pater Noster was built in 1868 to replace a light on Carlsten fortress in Marstrand, following plans for a lighthouse on the island dating from the 1750s. It was designed by engineer Nils Gustaf von Heidenstam and originally ran on colza oil, with a paraffin lamp installed in 1887. The lighthouse was automated in 1964 and deactivated in 1977 in favour of Hätteberget. After restoration, it was returned to Hamneskär in 2007 and relit on 26 September 2007. In 2015 it was declared a state building monument.

The name Pater Noster comes from the Latin opening of the Lord's Prayer, "Pater noster...", and refers to the prayer itself as well as to the skerries. The boundary between the Kattegat to the south and the Skagerrak to the north runs from the Pater Noster skerries to the northern tip of Skagen in Denmark.

The lighthouse stands on Hamneskär, one of the Pater Noster islets in the Klädesholmen parish, reachable only by boat; a new harbour with concrete breakwaters and quays was built on the islet's east side in 1937. The former keepers' quarters now house a small hotel and conference centre, so overnight stays are possible. Cemented paths lead from the courtyard to the harbour and the tower.

The lantern room was fitted with a high-standard kitchen by furniture company Marbodal in 2015 as part of a PR campaign. In 2020 the Gothenburg Film Festival held a lottery, "The Isolated Cinema", whose winner watched premieres alone in that room for a week; over 12,000 people from more than 45 countries applied.