When Crixus and Naevia split from Spartacus they take 30,000 men with them. in Episode 5 they march to take Italy. Unfortunately they will be killed off and it'll be a victory for the romans. But also unfortunate for them too Spartacus comes just in time to slaughter them and turn around and slaughter the people following them.
Castus becomes a decent leader. and him and Gannicus will die in one of the very last episodes. Probably Episode 9. Most likely along with Saxa.
In the final battle D Knight told viewers he has to keep everything to the point and historically accurate. So Spartacus will lose the final battle and all his men will die along with him. 6,000 captured men will be crucified. Among them will be Nasir and Agron. Both of them will be taken down. by Spartacus and and they'll pretty much live happily ever after. Also Spartacus's body was never found so that is why he get's to live. Agron and Nasir are fictional characters. Also why they get to live. Gannicus and Castus unfortunately are not fictional and then for must die. Sorry to all Gannicus fans.
Spartacus will have a love relationship with the roman woman and thus have a reason to start his life.
*Ending Spoilers*
Rebels Deaths
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Crixus
Naevia
Castus
Gannicus
Lugo
Nemetes
Roman Fatalities
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Possibly Tiberius. I have not found any research that states such that he is a real life character. Thus he could be killed off.
