Yekaterina Ivanovna Nelidova (1756–1839) was a Russian noble and lady in waiting. She was the royal mistress of Tsar Paul I of Russia.
Nelidova graduated from the Smolny Institute in 1776 and became a lady in waiting of first Grand Duchess Natalya and then Grand Duchess Maria. She had a relationship with Grand Duke Paul, the future monarch, and acted as a successful mediator between him and people he was in conflict with. Her position also acquired her relatives with positions at court. She left her position at court in 1798.