A program is underway at SLAC to develop a Marx-topology klystron modulator for the International Linear Collider (ILC) project [1]. It is envisioned as a smaller, lower cost, and higher reliability alternative to the bouncer- topology baseline design. The application requires 120 kV ( /-0.5%), 140 A, 1.6 ms pulses at a rate of 5 Hz. The Marx constructs the high voltage pulse without an output transformer, large at these parameters, by instead combining a number of lower voltage cells in series. The modularity of the Marx topology can be further exploited to achieve a redundant, high-availability design. The ILC Marx employs solid state elements; IGBTs and diodes, to control the charge, discharge and isolation of the cells. The SLAC designs are oil-free; air is used for high voltage insulation and cooling. Integration of the first generation prototype, P1, into an Lband test station for life testing of klystron and modulator is nearing completion. Development of a second generation prototype, P2, is underway. Status updates for both prototypes are presented. Show Partial Abstract