Sir Subbier Subramania Iyer KCIE (Tamil: சுப்பையர் சுப்பிரமணிய ஐயர்; 1 October 1842 – 5 December 1924) was an Indian lawyer, jurist and freedom fighter who, along with Annie Besant, founded the Home Rule Movement.

His father Sooravally Subbier Aiyer (1794–1844) was the legal agent of the Raja of Ramnad's zamindari, but died when Subramania Iyer was barely two years old.

As his mother was not willing to send him to Madras for a higher education, Subramania Iyer decided to join the administrative service.

In 1877, he gave evidence and pleaded for the necessity of protecting tenants from arbitrary eviction by the landlords, before the Famine Commission when it visited Madura.

After his wife, Lakshmi's death in 1884, he shifted to Madras, where he emerged as a formidable rival to the redoubtable lawyers Bhashyam Aiyangar and Eardley Norton.

After serving as a judge of the Madras High Court for 12 years, he resigned on 13 November 1907 due to failing sight, and was succeeded by Mr. Chettur Sankaran Nair.

One of the founding members of the Indian National Congress, he led the Madras delegation to its first session at Bombay, in December 1885, where he seconded a resolution proposed by K. T. Telang urging the increase of the elected element in the Legislative Councils and for councillors to be given real and effective powers, and where he made the following statement, as published in the annals of the Indian National Congress of 1885: "All of us have the utmost faith and confidence in the justice and the fairness of the English people, and we only have to solicit an enquiry into the facts, being content to leave the issue in the hands of their great political leaders.

He was close to Sir Arthur Lawley, whom he is held to have substantially influenced and assisted in his administration of the Madras Presidency, in a private capacity.

Immediately after Mrs. Besant was interned, Sir Subramania Iyer wrote a letter to Woodrow Wilson, President of the United States of America describing British Rule in India and appealing for the sympathy and support of the American Government and people, in which he stated: "Officials of an alien nation, speaking a foreign tongue, force their will upon us; they grant themselves exorbitant salaries and large allowances; they refuse us education; they sap us of our wealth; they impose crushing taxes without our consent; they cast thousands of our people into prisons for uttering patriotic sentiments-prisons so filthy that often the inmates die from loathsome diseases.

His interest in the scholarly aspects of law led to his residence, the Beach House on the Marina at Mylapore, being used for the "Saturday Club" that met at 11 a. m. every week, between 1888 and 1891, with all leading members of the Madras Bar participating, and cases being critically analysed.

He was the President of the Dharma Rakshana Sabha, which he founded in 1908, and which sought to prevent the mismanagement of the funds of Hindu Religious Endowment and Charitable Trusts.

As the President of the Suddha Dharma Mandala, which he founded, he was instrumental in publishing several important Hindu religious works.

His participation in the activities of the Theosophical Society gradually drew him closer to Annie Besant and the Indian independence movement.

The Government awarded a Certificate of Merit to Subramania Iyer on 1 January 1877 as a mark of their appreciation of his services to the public, on the occasion of the Proclamation Durbar at Delhi.