Warner Bros. Television has done such a good job of introducing characters into the Arrowverse over five years that now it seems like anybody could be added and it would work. But each of the series have a different tone, meaning that certain characters would make more sense on certain series. Here is a look at fan-favorite character I think should be brought into the Arrowverse through Legends of Tomorrow Season 3: Jack Knight, AKA Starman.
My first thought for Legends of Tomorrow was Adam Strange. He would fit in well with the crew of the Waverider, but I am still hoping they do a whole season based on the Planet Heist and Rann/Thanagar War story arcs…so not him this time. So Starman it is.
The series seems to like legacy characters with Steel, Vixen, and Canary in a way. They already introduced Stargirl as part of the Justice Society, why not bring us Starman? The version of Starman created by James Robinson and Tony Harris seems to be a good fit for the series and would result in some pretty interesting interactions with each of the members of the team. He'd be a kindred spirit with Nick Heywood, a connection to Amaya's past, someone to butt heads with Sara (the both have an attitude), and he would fascinate Stein and Palmer. The person who might have the least interest in him would be Jax, who Knight would probably get along with best.
Casting-wise they could go with Richard Madden (Robb Stark in Game of Thrones). He has the look, acting ability, and physique to pull off the character — plus a big enough following that whichever episodes he stars in could be the highest rated of the season. The show could just pick him up in the middle of one of his comic series story arcs where he has headed into space to find his girlfriend's brother (another Starman), where he gets waylaid in time and space. In the comics he ends up helping the Legion of Superheroes, Adam Strange, and Jor-El…so an assist with the Legends would fit right in.
Legends of Tomorrow Season 3 is set to premiere this fall.