Unit cells of metal oxide semiconductor (MOS) transistors are provided including an integrated circuit substrate an a MOS transistor on the integrated circuit substrate. The MOS transistor includes a source region, a drain region and a gate. The gate is positioned between the source region and the drain region. A horizontal channel is provided between the source and drain regions. The horizontal channel includes at least two spaced apart horizontal channel regions. Related methods of fabricating MOS transistors are also provided.