This years Superman Celebration, which is taking place on June 11-14 in Metropolis, Illinois, home of the Superman Museum will include several guest from DC Comics writers, artist as well as Superman and Non-Superman related TV guest such as:
Candice Patton (Iris West on The Flash)
Diane Sherry (Lana Lang in the 1978 Superman movie)
Stacey Haiduk (Lana Lang on Superboy)
Caity Lotz (Sarah Lance/The Canary on Legends of Tomorrow)
If there are any additions we will definitely update you on all of them.
Check out the website for further details: Supermancelebration.net