In Despicable Me 1, the minions were cool sidekicks.  In Despicable Me 2, they completely took over the movie (to the betterment of the film) and became a pop culture phenomenon.  Next summer Minions take center stage.  The spin-off film will star Sandra Bullock and a plot summary also accompanied the first look at the film:
Arriving on the big screen July 10, 2015, this Despicable Me spinoff begins at the dawn of time. Starting as single-celled yellow organisms, Minions evolve through the ages, perpetually serving the most despicable of masters. Continuously unsuccessful at keeping these masters—from T. rex to Napoleon—the Minions find themselves without someone to serve and fall into a deep depression.

But one Minion named Kevin has a plan, and he—alongside teenage rebel Stuart and lovable little Bob—ventures out into the world to find a new evil boss for his brethren to follow.

The trio embarks upon a thrilling journey that ultimately leads them to their next potential master, Scarlet Overkill (Academy Award winner Sandra Bullock), the world’s first-ever female super-villain. They travel from frigid Antarctica to 1960s New York City, ending in mod London, where they must face their biggest challenge to date: saving all of Minionkind… from annihilation.