Odo is the name of a shapeshifter on Star Trek: Deep Space 9, who doesn't know his origins or homeworld until around season 3. I guess the homeworld isn't revisited as a major plot point until season 6? I don't remember...seasons 6 and 7 were honestly kind of a blur for me.

http://memory-alpha.wikia.com/wiki/Odo

I think prior to season 6, the Klingons and Romulans tried to destroy the Dominion by taking out Odo's homeworld in a sneak attack. Odo's people turned out to be the rulers of a large empire that sought to conquer solids (non-shapeshifters).

Cardassians, not Klingons.

Also when Odo was forced to return to the Link to be judged (end of season 4).

Pretty sure that's a reference to http://memory-alpha.wikia.com/wiki/The_Search,_Part_II_%28ep... and http://memory-alpha.wikia.com/wiki/Great_Link .

Star Trek, Deep Space 9.

Odo is a shape-shifting being who is removed from his home planet. But we don't find that out til the 3rd season.