| William Kyriakos | |
| Fullname: | William Kyriakos Jr. |
| Birth Date: | 3 September 1972 |
| Birth Place: | São Paulo, Brazil |
| Careerprizemoney: | $27,531 |
| Singlesrecord: | 0–1 |
| Highestsinglesranking: | No. 266 (24 Jun 1991) |
| Doublesrecord: | 0–2 |
| Highestdoublesranking: | No. 244 (15 Feb 1993) |
| Medaltemplates-Expand: | yes |
William Kyriakos Jr. (born 3 September 1972) is a Brazilian former professional tennis player.
Kyriakos, who comes from São Paulo, represented Brazil at the 1991 Pan American Games in Havana. He won a silver medal in the mixed doubles competition, partnering Cláudia Chabalgoity, as well as a gold medal in the team event. The team of Kyriakos, Nelson Aerts and Marcelo Saliola defeated Puerto Rico in the final.[1]
On the professional tour, Kyriakos had a career best singles ranking of 266 in the world and made an ATP Tour main draw appearance as a qualifier at the Brasília Open, held once only in 1991. He lost in the first round to José Daher.[2]