Koceila Julien Mammeri (; born 23 February 1999) is a badminton player who trained at the Oullins club in France. Born in France, he represents Algeria internationally. In the junior event, he was the third place at the Portugal International tournament in the boys' doubles event. He won gold medals at the 2017, 2019, 2020, 2021 and 2022 African Championships for men's doubles with his partner Youcef Sabri Medel, and in 2018 and 2019 for mixed doubles with Linda Mazri, and also in 2021 and 2022 for mixed doubles with Tanina Mammeri. He claimed the mixed doubles gold medals at the 2019 African Games with Mazri and in 2023 with Tanina Mammeri.
Partnered with her sister Tanina Mammeri, the duo competed at the 2024 Summer Olympics.
Men's doubles
Mixed doubles
Men's doubles
Mixed doubles
Men's doubles
Men's doubles
Mixed doubles