Before season one began, producers had said that Adam Strange was not going to be the only modern-day hero to travel back to old Krypton. Rather, Hawkwoman was supposed to play a role as well. The character vanished without mention by the time the official season synopsis was released, and after the season wrapped up, showrunner Cameron Welsh said that they felt there was just
too much going on in the first season, and did not want to give Hawkwoman a short shrift. Of course, it sounds like the show might have to get a third season to actually see whoever shows up, since Ritson told us that they are simply "teased" in season 2's back half.
Besides joking (we assume) that he wants to bring back Brainiac's pet from the comics, Koko the space monkey, Ritson teased, “I can’t say who, but there are some other big names from the DC Universe which are teased at the end of this season, so there are some big characters arriving and it will be quite thrilling to interact with them when they arrive.”