An overhead mountable inflatable airbag assembly for a vehicle is disclosed. Inflatable airbag assemblies may provide protection for an occupant in a vehicle collision event. The disclosed airbag assembly may form a sideways V shape to be supported at the roof by an inflator, housing, or other mounting method, and at or near a lower (distal) end against a portion of an instrument panel or a rear portion of a forward occupant seat. The supported sideways V shape may support the occupant during ride down to provide protection of the occupant. The supported sideways V shape may also reduce the volume of inflation gas required to properly inflate the airbag assembly, and may reduce the overall packaged volume of the airbag assembly.