Conjeevaram Natarajan Annadurai, (C. N. அண்ணாதுரை) affectionately known as Anna ("Elder brother") or Arignyar Anna (அறிஞர் அண்ணா - "Anna, the scholar"), was an Indian politician who served as 1st Chief Minister of Tamil Nadu for 20 days in 1969 and fifth and last Chief Minister of Madras State from 1967 until 1969 when the name of the state of Madras was changed to Tamil Nadu. He was the first member of a Dravidian party to hold either post.

He was well known for his oratorical skills and was an acclaimed writer in the Tamil language. He scripted and acted in several plays. Some of his plays were later made into movies. He was the first politician from the Dravidian parties to use Tamil cinema extensively for political propaganda. Born in a middle-class family, he first worked as a school teacher, then moved into the political scene of the Madras Presidency as a journalist. He edited several political journals and enrolled as a member of the Dravidar Kazhagam. As an ardent follower of Periyar E. V. Ramasamy, he rose in stature as a prominent member of the party.

Annadurai was known as one of the best Tamil orators during his time. He developed a style in Tamil public speaking using metaphors and pleasing alliterations, both in spoken and written language. Anna was also best known for his extempore speaking ability being very well affluent on rhetoric skills.

After his electoral success with his DMK in 1967, the Congress has not yet returned to power in Tamil Nadu. His government was the first in the country to be from a non-Congress party with full majority.

Annadurai travelled to New York for medical treatment and he was operated for Cancer in the gullet at the Memorial Sloan Kettering Cancer Center. After he returned, he continued to address several official functions against medical advice. His health deteriorated further and he soon passed away. His funeral had the highest number of attendees until then, as registered with The Guinness Book of Records. An estimated 15 million people attended it. His remains were buried in the northern end of Marina Beach, which is now called Anna Memorial.