Dean Cain (Dr. Curtis Knox) previously played Clark Kent / Superman in Lois & Clark: The New Adventures of Superman (1993).
Vandal Savage is the antagonist in the first season of the series DC's Legends of Tomorrow (2016). In the episode "Night of the Hawk (2016)", he uses the alias "Dr. Curtis Knox".
At the end there is a PSA for the Christopher and Dana Reeve Foundation starring Dean Cain.
Dean Cain plays Curtis Knox, who is a version of the comics villain Vandal Savage. Phil Morris, who plays the Martian Manhunter voices Savage in the Justice League and Justice League Unlimited cartoon series
This episode marks the second of three DC Comics related live-action TV shows that Dean Cain has appeared in. The other two were as Clark Kent/Superman in Lois & Clark: The New Adventures of Superman (1993), and as Dr. Jeremiah Danvers, Kara Danvers/Supergirl's adoptive father in 6 episodes of Supergirl (2015).