A relativistically-correct Fokker-Planck analysis is used to develop fluid equations which model the interaction of relativistic electron beams with high atomic-number plasmas. The derived collision terms can be used to describe scattering and energy in materials ranging from the solid to high-temperature plasma forms. The full set of equations discussed can be used to study electron-beam-initiated pellet-fusion in a completely self-consistent fashion. Specifically, the model is applicable to study of beam pinching in plasma-filled diodes, the interaction of focussed beams with target plasmas, and the transport of high nu/gamma beams in high atomic-number plasmas. Although the general equations are amenable to solution only by computational techniques, analytic solutions describing the time-dependent, collisional interaction of a beam in an infinite plasma, and the one-dimensional equilibrium of a beam in a plasma with applied electric field have been obtained.