Naomi Watts has joined the cast of Warner Bros.’ “J. Edgar,” opposite Leonardo DiCaprio, Ed Westwick, Damon Herriman, Armie Hammer, Ken Howard and Josh Lucas.

Watts will portray Helen Gandy, the longtime personal secretary to FBI director J. Edgar Hoover. Gandy began working for Hoover in 1918 and continued in that role until he passed away in 1972.

Clint Eastwood is directing from a script by Dustin Lance Black (“Milk”).

Hoover was appointed director of the Bureau of Investigation in 1924 and was named head of the FBI when it was founded 11 years later.

Producers are Brian Grazer and Ron Howard through Imagine Entertainment along with Eastwood and producing Rob Lorenz through their Warner-based Malpaso banner.

Watts was last seen as Valerie Plame Wilson in “Fair Game” and will be seen next in “Dream House.”