Fantastic Four (1961) #400

A special 64-page anniversary issue! Aron the Rogue Watcher plucks villains from across the timestream to destroy the FF once and for all! But Aron himself must contend with one that is his equal - Uatu, Earth's true Watcher! Then, when the dust has settled, the Fantastic Four at last pay final respects to their dear friend and leader, Reed Richards.