John Smith "Jock" Garden (13 August 1882 – 31 December 1968) was an Australian clergyman, trade unionist and politician. He was one of the founders of the Communist Party of Australia.

Garden was born on 13 August 1882 in Nigg, Aberdeen, Scotland. He was the second son of Ann (née Smith) and Alexander Garden; his parents were both employed in the fishing industry.

Garden attended a state school at Lossiemouth. He was then apprenticed as a sailmaker with his cousin. His brother immigrated to Australia in the 1890s and the rest of the family joined him in 1904.

In 1906, Garden was a Church of Christ minister at Harcourt, Victoria. The next year on 6 May in Melbourne, with the forms of that church, he married Jeannie May Ritchie, from Leith, Scotland. By 1909 he was a member of the Labor Party and also a Baptist preacher at Maclean, New South Wales. In 1914 he was living at Paddington and working intermittently at his trade; he became the president of the Sailmakers' Union and its delegate on the Labor Council of New South Wales, which was to be his power base until 1934. In 1916 he was elected assistant secretary of the council, and in 1918 became its secretary. He failed as a Labor candidate at Parramatta in the 1917 State elections. Before that, Garden was employed from 1915 by the Department of Defence at its ordnance store at Circular Quay. In 1916 he was fined £10 for improperly accepting a gift from a supplier to the department and was dismissed on 14 March 1917 year after admitting that he had destroyed an important voucher.

Garden's oratorical style, coupled with a strong Scots' burr, ranged from captivating to ranting, adaptable to the pulpit and the Trades Hall. His speeches were quite often rambling tirades, but seldom unproductive. He read non-conformist and radical literature including Karl Marx and Vladimir Lenin enthusiastically after the 1917 Russian revolution. The times were auspicious for Garden on the Labor Council in 1916–18. World War I and conscription divided the Labor movement. In 1916 the Labor state premier, William Holman, along with other moderate politicians were expelled and formed the conservative National government.

The triumphant unionist wing, led by the Industrial Vigilance Council, became even more left wing. Some moderate unions left the Labor Council. The Industrial Vigilance Council tried to make the Labor Party the political arm of the One Big Union (OBU), a radical scheme. The Australian Workers' Union made the turmoil worse by trying to make itself a non-revolutionary O.B.U. with the support of some moderate politicians and unions. Garden was expelled in 1919 from the Labor Party for advocating revolutionary socialism. For a time he was a member of the Industrial Socialist Labor Party.

In November 1920 Garden announced the formation of the Communist Party of Australia, which he had initiated with William Earsman. Garden was prominent in 1921 at the All-Australian Trade Union Congress in Melbourne, which wanted to impose a positive socialist policy on the Australian Labor Party. He rapidly became one of its most prominent figures, leading a group of militant trade unionists known as the "Trades Hall Reds."

Under Garden's leadership the CPA concentrated on trying to gain control of the New South Wales trade unions, and through them to re-enter the Labor Party (which was based on affiliated trade unions). This led to a split in the CPA, with more radical members rejecting the attempt to re-enter the Labor Party. In 1922, however, Garden attended the Congress of the Communist International in Moscow, which endorsed his strategy. Although the Labor Party, under its parliamentary leader Jack Lang, rejected Communism, Garden as Secretary of the Trades Hall was a powerful figure in the labour movement, and in 1923 he was readmitted to the Labor Party and elected to its state executive.