Alla Grebennikova (Russian: Алла Гребенникова; born 24 February 1949) is a retired Russian breaststroke swimmer who won two medals at the 1970 European Aquatics Championships.

[1] She also competed at the 1968 Summer Olympics and finished fourth in the 4×100 m medley and 200 m breaststroke events.

[2] She married a Bulgarian swimming coach, Georgi Kostadinov (Bulgarian: Георги Костадинов), changed her name to Kostadinova, and moved to Bulgaria.

There she worked as a swimming coach and started competing in the masters category.

She finished second at the European (2001) and World championships (2004) in the same event.