South (Icelandic: Suður) is one of the six multi-member constituencies of the Althing, the national legislature of Iceland. The constituency was established as Southern (Icelandic: Suðurland) in 1959 following the nationwide extension of proportional representation for elections to the Althing. It was renamed South in 2003 when parts of Eastern and Reykjanes constituencies were merged into the Southern constituency following the re-organisation of constituencies across Iceland. South consists of the Southern and Southern Peninsula regions. The constituency currently elects nine of the 63 members of the Althing using the open party-list proportional representation electoral system. At the 2021 parliamentary election it had 38,424 registered electors.

South currently elects nine of the 63 members of the Althing using the open party-list proportional representation electoral system.^[4][5] Constituency seats are allocated using the D'Hondt method.^[6][7] Compensatory seats (equalisation seas) are calculated based on the national vote and are allocated using the D'Hondt method at the constituency level.^[8][9] Only parties that reach the 5% national threshold compete for compensatory seats.^[7][10]