system
Given the following post, respond as if you're commenting on Reddit:
human
[Warhammer 40K] Does the Imperium have GI Joe/Power Rangers style shows starring Space Marines?
gpt
Yes and no. Because of how fractured the Imperium, you won't see the Harriers winning the Cup broadcasted live over a dozen worlds (if the Harriers even get to the finals). Each world will have its own culture, and thus entertainment, but you won't have any constants because if how absurdly diverse the Imperium is. 

Some worlds, like Catachan or Krieg, will have no culture beyond surviving and venerating the Emperor because of their status as a Death World, while Pleasure worlds or upper class hive spires will have things like plays or circuses. 

As for specific shows staring Space Marines, it would be unlikely. They are the Emperor's holy warriors and venerated as such. You will get massive parades and celebrations to commemorate their glorious victories, not the latest installment of CSI: Ultramarine staring Uriel Ventris.