After weeks of unofficial confirmation, Marvel has finally given the definitive nod; Aaron Taylor-Johnson and Elizabeth Olsen are joining Avengers: Age of Ultron as brother-sister duo Quicksilver and the Scarlett Witch.

It hasn't been the best kept secret in Hollywood - rumours of their casting began in August and Samuel L. Jackson even told the Wall Street Journal that Mary-Kate and Ashley's little sister had signed up.

Olsen and Taylor-Johnson must have good chemistry (eww, but they are playing brother and sister!) since they are playing husband and wife in upcoming monster flick Godzilla and I'm sure we'll all agree that they will both look damn good on screen together.

Blockbuster Avengers: Age of Ultron will also star Robert Downey Jr, Scarlett Johansson, Jeremy Renner, Chris Hemsworth, Chris Evans, Mark Ruffalo and James Spader and is set for a summer 2015 release.

Remind yourself of how fun the first Avengers movie was by watching the trailer: