Alan William James Cousins (8 August 1903 – 11 May 2001) was a South African astronomer.
He was the eldest of four children, and his father Clarence Wilfred Cousins was a senior civil servant who served for a time as Secretary of Labour. His grandfather on his mother's side was Sir James Murray, first editor of the Oxford English Dictionary, and Cousins attended Murray's funeral at age 11.
He singlemindedly devoted himself to photometry and its improvement. The version of the UBVRI that he devised became the standard.
He became a Fellow of the Royal Astronomical Society in 1941. He won the Jackson-Gwilt Medal of the Royal Astronomical Society in 1971.
He had two children.