Currently there are 32 native Wideangle Prime lenses for Olympus E-M1 and 16 of these lenses are autofocus (AF) type.
E-M1 also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on E-M1.
Since Olympus E-M1 has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 6 Wideangle Prime lenses with Weather Sealings.