I read that the Daleks from Doctor Who put their creator, Davros, on trial. Does anyone know if they killed him, or at least what happened to him afterward?
This happens in the Sixth Doctor story Revelation of the Daleks, broadcast in two parts in March 1985. From Wikipedia's plot summary:
Daleks loyal to the Dalek Supreme arrive from Skaro, called by Takis who now realises what has been going on. Takis leads the grey Skaro Daleks to Davros' laboratory, where they are met by cream and gold Necros Daleks who are loyal only to Davros. A battle ensues, during which Davros' only usable hand is shot off by Orcini. The grey Daleks then take Davros to Skaro to stand trial.
However, the audio story The Juggernauts, first released in 2005, revealed that Davros never actually stood trial - the prison ship that was carrying him crash-landed on the planet Lethe, allowing Davros to escape his captors. So no, the Daleks didn't kill him or do anything else to him, because they never got the chance.
It's worth noting that the Daleks have attempted to kill Davros on multiple other occasions. Notably, the first story he appears in, Genesis of the Daleks, ends with him being shot and seemingly killed by his own creations when they realise he is not a Dalek himself and thus "impure". However, Revelation of the Daleks was the only time they attempted to make him stand trial.