Eliza Lynch (1835? - 1884) was the mistress of Francisco Solano López, the president of Paraguay.

She was born in Cork, Ireland, and emigrated with her family to Paris to escape the Potato Famine ten years later.

Eliza Lynch met Francisco Solano López, son of Carlos Antonio López, president of Paraguay, while working as a Parisian courtesan in 1854. She returned to Paraguay with him in 1855 and spent the next 15 years as the most powerful woman in the country.

When López became president in 1862 she became de facto first lady (they never married). She supported him in his disastrous wars which led to the deaths of over three hundred thousands Paraguayans. Despised and reviled, she was expelled from the country in 1870 (following the death of López) and died in obscurity in Paris. Over one hundred years later, in an extraordinary act of rehabilitation, her body was exhumed and brought to Paraguay where she was proclaimed a national heroine.

Some people believe that Eliza Lynch was responsible in inducing Francisco Solano López to start the Paraguayan War.

She is the subject of the 2004 novel The News From Paraguay by Lily Tuck, winner of the National Book Award for that year.