Krypton-fluoride lasers have been shown to be promising candidates for inertial confinement fusion (ICF) drivers. These lasers can be effectively pumped with electrical discharges or energetic electron beams (e beams). With discharge pumping, the laser aperture is limited in size to a few centimetres (at atmospheric pressure) because of discharge instabilities that cause a homogeneous discharge to degenerate into arcs. Much larger aperture lasers can be pumped using relativistic e beams. At Los Alamos National Laboratory (LANL), we are constructing high-energy e-beam-driven KrF lasers with apertures as large as 1 m2 for the ICF program. In designing and building these lasers, a number of physics and engineering issues related to large area electron guns (e guns) must be addressed. Among these issues are the following: generation of the relativistic e beams, transport of the e beams into the laser gas, and design and construction of pulsed power devices for driving the e guns. Cold cathode e guns are found to be useful sources for driving these large volume KrF lasers. Presented are some brief background comments on cold-cathode sources. We will also discuss the cathode current emission mechanisms, basic beam transport considerations, pulsed power devices for powering these e guns, and measured e-gun performance. Particular emphasis is given to practical considerations related to the two main LANL KrF/ICF laser systems: the 10-kJ Aurora system and the 100-kJ power amplifier module design.