Star Wars Rebels certainly isn't shy about bringing character from Clone Wars to the current series. With Ahsoka and Captain Rex regular appearing in the second season, it seems it will only be a matter of time before even the most obscure characters surviving the earlier program may shop up to help or hinder Ezra and the crew of the Ghost.
For instance, Sci Fi Central (via Jedi News) reports Battlestar Galactica veteran Katee Sackoff will reprise her role as Mandalorian Bo-Katan Kryze in the upcoming third season. The actress herself made the announcement at Sydney Comic Con:
Katan was a member of the Death Watch during the Clone Wars, but came into conflict with Darth Maul when he resurfaced. One imagines she's still ready to settle their old score.
Star Wars Rebels returns September 24th on Disney XD.