Power Girl and She-Hulk
The first season of Supergirl ended with the title character looking surprised at the unseen passenger of a rocket.  Was it Krypto, Superman, her mother, or someone else?  Some have speculated that this could be the introduction of Power Girl into the series, which could be interesting as well.  For a character that has been cosplayed so much, it is surprising that we still have not seen an official live action version yet.