The Division of Grey is an Australian electoral division in South Australia. The division was one of the seven established when the former Division of South Australia was redistributed on 2 October 1903 and is named for Sir George Grey, who was Governor of South Australia from 1841 to 1845 (and later Prime Minister of New Zealand).

The division covers the vast northern outback of South Australia. Highlighting South Australia's status as the second-most centralised state in Australia, Grey spans 904,881 square kilometres (349,377 sq mi), over 92 percent of the state. The borders of the electorate include Western Australia, the Northern Territory, Queensland and New South Wales borders, in addition to much of the southern coastal border. The electorate spans to Marion Bay and Eudunda in the south. The main population centres of the electorate include Ceduna, Port Lincoln, Whyalla, Port Augusta, Roxby Downs, Coober Pedy, Port Pirie, Kadina, Maitland, Orroroo, Booleroo Centre, Peterborough, Burra and Eudunda.

Since 1984, federal electoral division boundaries in Australia have been determined at redistributions by a redistribution committee appointed by the Australian Electoral Commission (AEC). Redistributions occur for the boundaries of divisions in a particular state, and they occur every seven years, or sooner if a state's representation entitlement changes or when divisions of a state are malapportioned.

During proposed redistribution of electorates in South Australia after the 2025 Australian federal election, public submissions were requested for potential name changes to existing electorates. Grey was recommended to be changed to O’Donoghue in honour of Dr Lowitja O'Donoghue, a Yankunytjatjara woman and the first Indigenous nurse at the Royal Adelaide Hospital. She was also the inaugural chairperson of the Aboriginal and Torres Strait Islander Commission and a noted Indigenous rights advocate. The AEC agreed with the recommendation, citing O'Donogue's connection to the lands of the electorate and her work during her life. The AEC stated that while Sir George Grey had contributed to the establishment of the colony of South Australia, he was born and died outside Australia, and had little connection and contribution to Australia, while also citing a legal amendment he made in 1844 that stipulated that unsworn testimony from Indigenous people would be inadmissible in court.

When Grey was first created in 1903, it included the Northern Territory and all of northern and western South Australia, down to a line through the Mid North south of Port Pirie.

Following the 1949 redistribution it increased in size and covered almost five-sixths of the State of South Australia (111,000 square miles) from the borders with Western Australian and Northern Territory in the West and North to Queensland and New South Wales in the East. The remaining one-sixth of the State was covered by the other nine Federal Divisions for South Australia.

Grey was held by Labor for much of its history, and was one of the few country seats where Labor usually did well. It remained in Labor hands for all but one term from 1943 to 1993, the only break coming when the Liberals won it during their landslide victory in 1966. For most of that time, it was a fairly safe Labor seat, though it was almost lost in the Coalition landslides in 1975 and 1977.

That changed in 1993, when the retirement of Labor incumbent Lloyd O'Neil, the unpopularity of the state Labor government, and the addition of the Clare Valley at a redistribution which turned Grey in to a marginal seat, enabled Liberal Barry Wakelin become only the second non-Labor member to win the seat in 50 years. That happened even as Labor won another term; it was the first time Labor had won government at an election without winning Grey. However, the election came at a bad time for the state Labor government, which was roundly defeated at the state election later that year, at which Labor lost all but one seat within Grey's borders.