The disclosure relates to micro-electromechanical systems (MEMS) and magnetic MEMS sensors. The sensors include a substrate having a surface, a first magnetic field detector positioned on the surface, a second magnetic field detector positioned on the surface proximate to the first magnetic field detector, and a third magnetic field detector positioned on the surface proximate to the first and second magnetic field detectors. Each of the first, second and third magnetic field detector is capable of detecting external magnetic fields that are mutually orthogonal along three directions. In certain embodiments, the magnetic MEMS sensors may be useful as electronic compasses. The disclosure also relates to fabricating a magnetic MEMS device, such as an electronic compass, from or on a single wafer, which includes multiple MEMS sensors.