|Roswell: Cry Your Name (2001) [Alex Whitman]: Dies (off-screen); his death is reported as a car accident, but the subsequent episode Departure revealed in flashback that Emilie De Ravin had accidentally killed him when she tried to mind-wipe him, and arranged the "accident" to cover it up. (Thanks to Alex and Shollum)
Untraceable (2008) [Agent Griffin Dowd]: Burned to death/dissolved by acid after Joseph Cross places Colin in a tank of water, rigged so that the acid is poured into the tank as more people log onto Joseph's website. His body is shown again later on when Diane Lane arrives at the scene.
Dexter: This Is the Way the World Ends (2011) [Travis Marshall]: Stabbed in the chest by Michael C. Hall after Michael drugs him and ties him to a table, while Jennifer Carpenter looks on in horror. (Thanks to Stephen)