The Arabian Leopard Panthera pardus nimr, classified by IUCN as “Critically Endangered”, is Saudi Arabia’s flagship predator. The population of this species has declined to approximately 50 individuals and may become extinct in the Arabian Peninsula if threats are not addressed. In addition to habitat destruction, major threats include poaching and competition for diminishing prey species, two factors which may have been underestimated so far. The main competitors of the Arabian Leopard are the Caracal (Caracal caracal schmitzi) and Arabian Wolf (Canis lupus arabs). With a Population Viability Analysis (PVA), we simulated various scenarios to demonstrate the impact of competition for prey and poaching. The population under stable natural conditions without poaching and restocking (supplementation) would have a survival probability of only 37%. Without competition by the Caracal, survivability of the leopard population would increase to 89%, and without the Arabian Wolf to 98%. The likelihood of extinction would be 1% if both competitors were absent. A second set of scenarios, with a poaching rate of six individuals per year, shows that the leopard would not survive over the next 100 years. Further, the stabilization of the population by means of restocking with captive-bred animals was simulated to test a minimal number of individuals required to substitute the Arabian Leopard population. In addition to the competition by Caracal and Wolf, supplementing a minimum of eight individuals would stabilize the population as it is now, and allow a maximum of six poached individuals per year. Our results demonstrate need for urgent protection of the Arabian Leopard as well as its prey with strict minimization of poaching. Our model, however, does not take into account the effect of habitat destruction and fragmentation, which may also have detrimental impacts to the leopards and associated species.