Arrow

Another DC villain been added to season 4 British Actor Jimmy Akingbola been cast as the villain Baron Blizkrieg in the comics he was a nazi super villain but in Arrow he will be known as Baron Reiter his story will mostly be told in flashbacks and will be a rival of Oliver.

Sara Lance (Caity Lotz) is resurrected as white canary in episode 8 of arrow season 4 before appearing in legends of tomorrow

http://comicbook.com/2015/07/22/sara-lan...gends-of-/

Jeri Ryan (Seven of Nine from Star Trek Voyager) will be the guest star in episode 2 of season 4

http://comicbook.com/2015/07/23/star-tre...-season-4/

Hawkman to appear in Arrow then The Flash before joining The Legends of Tomorrow.

yeah, hawkman and hawkgirl. it would be funny if Michael shanks were to play hawkman.

Doubt that will happen with the Smallville version being a different universe it will be a new actor.

Arrow Ep 1 of season 4 will take five months after the season three finale along with the new suit he will also have a new set of skills bringing him closer to the comic version of Green Arrow.

Another villain joining the cast for season 4 actor Ryan Robbins will be cast as a villain called Conklin who is a member of a criminal organisation Shadowspire, we'll possibly see the character in flashbacks.

Actor Falk Hentschel has been cast as Hawkman and will appear in Arrow, The Flash and Legends of Tomorrow.