| Sid Riley | |
| Birth Name: | Sidney Austin Riley[1] |
| Birth Date: | 18 April 1878 |
| Birth Place: | Auckland, NZ |
| Death Place: | Auckland |
| Ru Position: | centre |
| Repyears1: | 1903 |
| Repteam1: | Australia |
| Repcaps1: | 1 |
| Reppoints1: | 0 |
| Sid Riley | |
| Fullname: | Sidney Austin Riley |
| Club1: | Ponsonby United |
| Year1start: | 1910 |
| Year1end: | 1912 |
| Appearances1: | 20 |
| Tries1: | 6 |
| Goals1: | 3 |
| Fieldgoals1: | 0 |
| Points1: | 24 |
| Teama: | Auckland |
| Yearastart: | 1908 |
| Yearaend: | 12 |
| Appearancesa: | 8 |
| Triesa: | 1 |
| Goalsa: | 0 |
| Fieldgoalsa: | 0 |
| Pointsa: | 3 |
| Teamb: | New Zealand |
| Yearbstart: | 1912 |
| Appearancesb: | 1 |
| Triesb: | 0 |
| Goalsb: | 0 |
| Fieldgoalsb: | 0 |
| Pointsb: | 0 |
| Retired: | yes |
Sidney Austin Riley (18 April 1878 – 31 March 1964) was a rugby union player who represented Australia.
Riley, a centre, was born in Auckland, New Zealand, and claimed one international rugby cap for Australia, against New Zealand, at Sydney, on 15 August 1903. He also played rugby league in a match for New Zealand against Auckland and played for Auckland several times and was a member of the Ponsonby rugby club and Ponsonby United rugby league club.