Halo mass function at z = 0 for the Horizon-AGN, Horizon-noAGN, Horizon-Large, and Magneticum simulations in red, purple, green, and blue, respectively, with their associated Poisson noise as error bar. Each mass function is computed up to the maximal halo mass in the corresponding simulation. The analytical mass function from Sheth & Tormen (1999) is shown in black for comparison. Vertical lines indicate the minimum halo mass accessible in each simulation, defined as 100 times the dark matter mass resolution. The lower limits for Horizon-AGN and Horizon-noAGN are identical.