Olivia Mariamne Devenish (16 February 1771 – 26 November 1814) was the wife of Sir Stamford Raffles, vice governor of Java (1811–1816) from 1805 to 1814.

Olivia was married in Madras in 1793 to Jacob Cassivelaun Fancourt, who died in 1800, and in 1805 in London to Thomas Stamford Raffles.

While Stamford Raffles was governor on Java, she introduced many social reforms in her capacity as first lady, which set the standard for the rest of the century.

At this point, the Western colonists at Java mixed their European habits with East Indian ones: for example, white women born in the East Indies used areca catechu, and they only dressed in European fashion on official occasions, such as going to church, receptions and visits, and otherwise wore the more comfortable Asian dress kebaya and sarong.

[2] Devenish banned the common use of chewing areca catechu by Western women, and removed the pots for this from the reception rooms of the governor's residence to prevent her guests from using it.