When someone asks you what a giant bat looks like, just show them this picture (taken by one Allen Olaez here in the Philippines).
The giant golden-crowned flying fox gets its species name from the golden fur around the head, in sharp contrast to the black body. Like all other fruit bats, they have no tail. They are among the largest bats, with a wingspan of 1.5–1.7 m (4 ft 10 in–5 ft 7 in) and weighing 0.7–1.2 kg (1.5–2.6 lb).
and it does look huge, despite a little bit of play with the visual cues -- check out the positioning of the tree that it's attached to.
I'd freak out if this thing came diving at my face; thank god they eat fruits.
And yes, it is a megabat.