Family-friendly films always stand a shot at success, and Ben Stiller knows this better than most. The Madagascar franchise to which he lends his voice has grossed almost $2 billion across its three existing entries, and his two Night at the Museum movies have made a billion bucks between them. Come Christmas, Stillers Larry Daley will travel the globe for some reason as Night at the Museum: Secret of the Tomb hits screens in December to bring the unlikely trilogy to a close. The first Night at the Museum film was a surprise smash, taking home almost $600 million in 2006 to finish up as one of the years highest grossers. The Battle of the Smithsonian sequel three years later also did well, so the audience is clearly there for Stiller and his unwieldy gaggle of walking, talking museum exhibits.Why the Guardians should be worried: Secret of the Tomb has its work cut out to get near Guardians level of success, but it does have the Christmas holidays, excitable children and accommodating parents in its favour. Theres some stiff competition in and around its release, but Stillers co-star Rebel Wilson is on a hot streak and the presence of Robin Williams in one of his last performances should see this one come close to its predecessors totals.