Although all the <em>Rogue One</em> deaths are sad, I think one of the saddest has to be K-2SO while he fights off and buys time for Jyn and Cassian to get to the top of the tower to transmit the Death Star plans to the Alliance. However, that might be tied with Chirrut Îmwe and Baze Malbus' shared demise with all the Deathtroopers.
