Selwyn John "Sel" Muller (18 October 1917 – 24 February 2008) was a dairy farmer and member of the Queensland Legislative Assembly.^[1]

Muller was born in Boonah, Queensland, to parents Adolf Gustav Muller and his wife Annie (née Lobegeiger) and attended Kalbar State School and Boonah High School. He became a farmer and grazier in the Boonah district. In World War Two he was assigned to the 7 Division Cavalry Regiment reaching the rank of Lieutenant.^[1]

On 14 August 1950 Muller married Patricia Margaret O'Callaghan (died 1988) and together had one son and one daughter. He died in February 2008 and was buried in Kalbar General Cemetery.^[2]

Muller represented the state seat of Fassifern from 1969 until 1983, taking over the seat from his father, Alf Muller. He was the Speaker from 1979 until 1983.^[1]