Femtosecond electron diffraction data of nickel measured at the Fritz Haber Institute in Berlin. The dataset contains measurements at 3 different excitation wavelengths (2300 nm, 800 nm and 480 nm) and several excitation densities each. The sample was a polycrystalline film with a thickness of 20 nm, sandwiched between two layers of silicon nitride with a thickness of 5 nm each. More information is available here: https://doi.org/10.1103/PhysRevResearch.3.023032