Describes the known deformation types of compact hyperkähler (irreducible holomorphic symplectic) varieties — K3 surfaces, the two infinite families of K3^[n]- and Kum^n-type, and O’Grady’s sporadic OG6 and OG10 types — with the focus on deformation-invariant properties. For each type it records Betti and Hodge numbers, Chern numbers, the Beauville-Bogomolov-Fujiki form, number of moduli, monodromy group, Riemann-Roch polynomial and an interactive Looijenga-Lunts-Verbitsky decomposition of the cohomology.