Käty van der Mije-Nicolau (22 July 1940 – 14 October 2013), born Alexandra Ekatarina Nicolau, was a Dutch-Romanian chess player and Woman Grandmaster.

She was awarded a permanent residency and later Dutch nationality when she married Kees van der Mije.

[1] Nicolau had earlier resided for several months in the Netherlands after a tournament; she lacked permission from the Romanian government to do so.

In 1969 she wished to study at Leiden University; however, while completing formalities in Romania, she was not allowed to return to the Netherlands and was banned from playing international chess tournaments.

[4] Van der Mije has said she was not fanatical enough to only spend her time on chess, as she also liked to read detective stories and visit museums.