These monsters are described in Manual of the Planes: air element creature, anarchic creature, armanite, astral dreadnought, axiomatic creature, bariaur, canoloth, cold element creature, dao, dusk beast, earth element creature, ecalypse, fire element creature, firre, githyanki, githzerai, goristro, half-elemental, ice paraelemental, kolyarut, leonal, magma paraelemental, marid, marut, mercane, mezzoloth, narzugon, nycaloth, ooze paraelemental, petitioner, shadow creature, smoke paraelemental, spinagon, ultroloth, umbral banyan, uridezu, water element creature, wood element creature, xag-ya, xeg-yi, zelekhut.
The Modrons web enhancement adds these creatures: decaton, duodrone, hexton, monodrone, nonaton, octon, pentadrone, Primus, quadrone, quarton, quinton, secundus, septon, tertian, tridrone.