Whatever you want to call the universe of characters building up on the CW, the Arrowverse is expanding once again and this time its gaining Vixen. The animated series Vixen will take place in the Arrow and Flash universe with both costumed heroes making an appearance. The show will run on CW Seed, the network’s on-line presence and debut this fall. The series will be headed up by Arrow producer Marc Guggenheim. This was announced at the Television Critic’s Association press tour this morning.