The aim of this work is to study the microstructure of four high entropy alloys (HEAs) produced by large scale vacuum die casting. Al40Cu15Mn5Ni5Si20Zn15, Al45Cu15Mn5Fe5Si5Ti5Zn20, Al35Cu5Fe5Mn5Si30V10Zr10, and Al50Ca5Cu5Ni10Si20Ti10 alloys formed a mixture of different structures, containing intermetallic compound (IC) and solid solution (SS) phases. The phases observed in the casting alloys were compared with the equilibrium phases predicted by Thermo-Calc. The measured densities varied from 3.33 g/cm−3 to 5.07 g/cm−3 and microhardness from 437 Hv to 887 Hv. Thus, the microhardness and estimated strength/density ratios are significantly higher than other lightweight high entropy alloys (LWHEAs).