Terminator 2: Judgment Day is the only movie you ever saw your dad cry at until you Saving Private Ryan together. In the final act--spoiler alert for a twenty-five year-old movie--the titular Terminator T-800, now reformed and John Connor's new best friend, asks heroine Sarah Connor to lower him into the foundry, ending any future threat from SkyNet or the Terminators.
What follows is the saddest damn thing I had ever seen as a child because my favorite murder-bot is slowly lowered into molten hot metal and liquefied, but the last thing you see is the Terminator giving the teary-eyed Connors a thumbs up, so that they know they've done the right thing.
In Bethesda's DOOM reboot coming soon, they included a fun (read: terribly heartbreaking) callback to the best of the Terminator films when you character, The Marine, or DoomGuy, jumps into a pit of molten lava:
I swear I'm not crying. My eyes are just sweating because of all the molten metal in here.