* Titanic (1997): With a worldwide gross of over $2.2 billion, Titanic holds the record for the second highest-grossing movie of all time (adjusted for inflation), only surpassed by Avatar.
* Harry Potter: The entire Harry Potter film series has a combined worldwide gross of over $9.2 billion. While individual films are not the top earners, the franchise as a whole is a box office juggernaut.
* Twilight: The Twilight saga has a combined worldwide gross of over $3.3 billion.
Therefore, the Harry Potter film series has made the most money out of the three franchises.
While Titanic is still a top earner, its box office performance was based on a single film. Harry Potter's success comes from the eight films in the series, building upon the already established popularity of the books.