Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Tear Jerker: Being Human
The season three finale. Very nearly all of it.
The way that George delivers the line "You are not my friend" to Mitchell after being let out of the cage. Russell Toveys delivery makes it sound less like he is saying Mitchell is not his friend, but more like the person he is talking to is no longer his Mitchell, that "His friend" is already gone.
McNair's final letter to Tom, written before Herrick killed him. "Don't avenge me." Even sadder because he doesn't listen.
George's scream when he thinks Nina is dead. Words cannot describe it.
Lia's realization that her revenge on Mitchell will have the same effect on George as her death had on her family.
The build-up to George staking Mitchell. First Mitchell's attempts to convince George to do it by telling him that their entire friendship was a sham, and that George is pathetic. The fact that George knows he's lying is a Tear Jerker by itself. Then, when Mitchell doesn't have the heart to keep that up, he breaks down and begs George to do it because he knows he'll kill again. Finally George agrees. Mitchell says he's finally doing the decent thing, and Nina says this is what they'll remember him by. He tells Annie that she's the love his life. When Wyndham interrupts them, we think that this is a reprise (albeit not a particularly good one). Wyndham informs Mitchell he'll have to be an "attack dog" for the Old Ones, or else he'll "crucify" George and Nina. George picks up the stake, apparently to kill Wyndham, then turns around and rams it into Mitchell's heart.
George: I'm doing this because I love you.
Mitchell: I know.
Believe it or not, it gets worse in Series 4.
Nina was killed by the vampires shortly after giving birth, after George encouraged her to go outside.
George is killed in the first episode. His last words are to name the baby Eve. And then he becomes a ghost, standing behind his own dead body, in front of his door.
George: I have to be with my Nina.
Oh, and the reason he dies.? He forced his body to begin changing into a werewolf to save his daughter, but was unable to heal himself.
The worst part? She never got to read it. She dies while still a baby.
The ending of eighth episode of season three is probably one of the few actions that combines this with Crowning Moment Of Awesome.
George's death during the season four premiere.
Kirby tricking Tom into thinking that he was going to get his very first birthday party, complete with cake. The look on Tom's face when he realises that no one even knows that it's his birthday.
Annie falls for Kirby... who then begins to insult her until she fades away.
Kirby messes up Hal's bedroom and it looks like he can almost cope with that... Then he drops Hal's photo of Leo on the floor and Hal looks completely devastated.
Tom sending away Allison despite their mutual attraction because he knows he's turning her into a worse person, by pretending that he hates her, even though they both know it's not true.
The flashback to Cutler's past when Hal murders Cutler's wife and tricks him into drinking her blood.
Of course, Cutler repays him in kind, killing Alex and tricking Hal into drinking her blood. Both of them are devastated, with Hal even begging Cutler on his knees to stop his plot.
While on that note, Alex's reaction to her death. She mostly is pissed off at the vampires, but starts to break down when she realizes that her family will have no idea what happened to her. She returns to make sure the police find her body, and sees it covered in coagulated blood and maggots. She asks Hal to remove the tubes used to drain her blood, so that her parents won't be even more upset.
Annie's goodbye to future Eve, who tells her she was a good mum, and Annie says that she's proud of Eve.
Cutler's death. Yes, he was trying to kill Eve but he's spent so long being looked down on by the other vampires, never respected, always humiliated and he finally thinks people will remember him, know his name... and they won't.
Annie setting off the bomb and going through the door. Her smile when she opens the door and apparently sees George, Nina and possibly Mitchell.
Any scene from Series One of Mitchell, George and Annie being happy can be a tearjerker if you go back and re-watch it after you've seen Series' Three and Four and found out what later happens to them.
Alex breaking down one she finds that her family is now moving on after her death, that she doesn't know how to move on to the afterlife, and she can't enjoy normal human things like eating and relationships.
Tom sympathises by showing how crap his life is, that he hasn't had a proper life, he acts old-fashioned to try to keep his dead dad's spirit alive, and he's afraid to have children as he might kill them.
Tom regressing to just living in the woods, with the money for a tombstone for his father stolen, just because Larry took advantage of him and persuaded him that he's a beast of a man doomed to amount to nothing.
Bobby remembering how he transformed into a werewolf for the first time, and slaughtered his own family at his twelfth birthday party
Also Bobby revealing why he's obsessed with a certain model of answering machine, the last kind to use tapes. He has a tape of messages from his mother, which he hasn't been able to hear since his machine broke in 1996.
Hatch driving Bobby to suicide. He was finally happy for the first time in decades, ready to embrace life and all his opportunities, then Hatch tore it all away out of spite for ruining his plan.
Crumb and Hal's meditation. Crumb remembers a day-out with his niece, and how her screams of joy on a roller-coaster were so similar to her screams when he killed her mother, his sister. Hal remembers how he killed his love 200 years ago, feeling no restraint, and she just stared at him with disappointment.
Tom's crushed expression when he discovers that Hal's been drinking Natasha's blood, thinking that he forced her. After a moment of non-belief, he strides out of the house with a stake to kill Hal.
Natasha's death. Hatch controls her into slitting her throat in front of Hal to frame him. Meanwhile Hal desperately unties himself to save her, then just cradles her body when he realises she's gone.
When Hal realises that Alex and Tom think that he is genuinely capable of killing her, he gives up all hope of being clean and clinging onto humanity. So he goes into a pub and massacres the inhabitants.
When Hatch offers all the housemates a what he believes is their paradise - Tom gets to live free of the curse with Allison, a child soon on the way. Alex gets to be alive with her family again but Hal's paradise is simply that he gets to die on the field of Orsha, having been stabbed through the stomach with a lance. It shows so much about the character that bleeding to death in horrible pain counts as a paradise.