No, thorium is not a new character in the Avenger movie series. it is a a potential nuclear fuel.
Before you start reaching for your “No Nukes!” protest banners, check out this article form BI on how thorieum reactors are different. For one thing, they are safer. For another, they could provide nearly limitless energy for mankind.
This sounds to me a bit like the shift from coal to oil that fueled the 20th century. Pretty exciting stuff!