| Honorific-Prefix: | The Honourable |
| Selwyn Muller | |
| Office: | Speaker of the Queensland Legislative Assembly |
| Term Start: | 8 August 1979 |
| Term End: | 17 October 1983 |
| Predecessor: | Jim Houghton |
| Successor: | John Warner |
| Constituency: | Fassifern |
| Constituency Am1: | Fassifern |
| Assembly1: | Queensland Legislative |
| Term Start1: | 17 May 1969 |
| Term End1: | 22 October 1983 |
| Predecessor1: | Alf Muller |
| Successor1: | Kev Lingard |
| Birth Date: | 1917 10, df=yes |
| Birth Place: | Boonah, Queensland, Australia |
| Death Place: | Boonah, Queensland, Australia |
| Restingplace: | Kalbar General Cemetery |
| Birthname: | Selwyn John Muller |
| Nationality: | Australian |
| Party: | Country Party/National Party |
| Spouse: | Patricia Margaret O'Callaghan (m.1950 d.1988) |
| Occupation: | Dairy farmer |
| Relations: | Alf Muller (father) |
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]