Gold digger

A gold digger is a person, usually a woman, who has a relationship for money and/or goods rather than love. If the woman gets married, it's a marriage of convenience.
This type of relationship is called gold digging. 
The term "gold digger" was a slang term which has its roots in the 20th century. It is especially popular with chorus girls and sex workers.
"Gold digger" rose in usage after the popularity of Avery Hopwood's play "The Gold Diggers" in 1919.
Songs about gold diggers include "Gold Digger" from Kanye West and "Gold Digger" from EPMD. Both reference women marrying for money.