They all offer skills and approaches that work in well with their team-mates. And the banter among them makes for some very funny lines.
But ultimately, Avengers is all about the action and how the superheroes can protect the world.
Ultron is a prototype Stark has been working on to be the ultimate protector of the Earth long after the Avengers have gone.
When Ultron gets reprogrammed with an artificial intelligence a formidable opponent has been created.
And rather than protect the Earth, Ultron is intent to replicate and upgrade himself to be an indestructible force.
When his ultimate aim of destroying life on Earth becomes apparent, the Avengers need as much help as they can find. Former foes and now allies, Quicksilver and Scarlet Witch, join the fight.
Complicating their mission is the imminent destruction of a small European village and all its inhabitants.
It is very easy to love the Avengers franchise. The action is second to none and the characters are individually and collectively a lot of fun.
It is pure escapism of the highest order.
Avengers: Age of Ultron (M)
141 minutes
Rating: 4/5 stars