Margaret Nyairera Wambui (born 15 September 1995) is a Kenyan middle-distance runner specialising in the 800 metres.

[2] In her first international competition, she won the gold at the 2014 World Junior Championships.

[5] That same year she competed at the 2016 Summer Olympics, setting a new personal best of 1:56.89 in the final, which also earned her a bronze.

[6] In 2019, it was revealed that Wambui was born with the 46,XY karyotype and an intersex condition after her qualification for IAAF women's competition was affected by the association's new regulations for athletes with XY disorders of sex development, testosterone levels above 5 nmol/L, and androgen sensitivity.

[7][8] She was one of the athletes whose cases were profiled in Phyllis Ellis's 2022 documentary film Category: Woman.