Penning ionization of C6H5X (X = F, Cl, Pr, I) upon collision with metastable He*(2(3)S) atoms was studied by two-dimensional (collision-energy/electron-energy-resolved Penning ionization electron spectroscopy. Partial ionization cross sections are found to be larger for ionization from orbitals having n and Jr characters. Interaction potentials between the target molecule and the He* atom were found to be highly anisotropic. Attractive interaction was dominated around the collinear access of He*(2(3)S) to C-F axis in C6H5F On the other hand, attractive interaction was localized around the out-of-plane perpendicular approach of He* atom to C-X bond (X = Cl, Pr, I). Attractive interaction for these compounds increases on going from C6H5Cl to C6H5I. Furthermore, the electronic factor due to the size of the halogen p orbitals and the conjugation between the benzene ring and the halogen atoms and also the steric factor due to the shielding effect were found to be important.