This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Hawaii Five-0
In "Malama Ka Aina"
Danno: Rachel, just hear me out. Before you sic your lawyers on me, I wanna remind you of something. I moved 5,000 miles so that I could see Grace twice a week. Twice a week, okay? That is 48 hours, 52 times a year for a grand total of 2,500 hours. When you factor in sleep, and school, I can really only count on 400 hours of real face time each year. And ya know? That's only going to shrink as she starts making friends... Then she goes off to college... So ultimately that does not leave me with a lot of time to spend with my daughter. Not as much as I would want. But I never complained. I never complained. Because every single one of those minutes reminds me of what I am doing, and why I am here. That little girl is my life. So I am asking you- I am begging you to please- please just be kind. Don't take her away from me, that's all.
In "Ho’onani Makuakane", where an ex-442nd Infantry Regiment veteran tells the Five-0 team about his life in Hawaii before and after his internment at the camps. And how he lost everything, including his family due to martial law when WWII started.
"Ina Paha". Good lord. Steve is tortured and drugged by Wo Fat (for information he doesn't have), said drugs making him hallucinate an Alternate Reality where his father is alive. After he kills Wo Fat and his team rescues him, the first thing he asks Danny is where his father is. After Danny gently reminds him his father died four years ago, Steve McGarrett, Made of Iron, Determinator, and all around Badass, breaks down and sobs. This Troper felt as gutted as he did.
"Kahania" has several moments in the A-plot - After protecting a gunshot victim from mob enforcers, McGarrett tracks down the man who made the hit, who reveals he's the victim's father. When McGarrett asks how he could put a hit on his own son, he explains that it's because his son's not the victim he led McGarrett to believe he was, but was actually behind the abductions & murders of several children. Later, McGarrett asks what tipped him off, as they'll need something to prove it - he directs McGarrett to room in a basement. As the door opens, the camera shows one single shoe left from a child, before panning upwards to reveal the room is full of them. As McGarrett enters the room, he picks up a stack of Polaroids, each one featuring a scared child, before eventually breaking down as he silently weeps.
Everything in "Moʻo ʻolelo Pu". An ex-meth cook going straight learns that his son is getting involved in the local meth trade and Kono doing a journey in the place of her mom because of her aneurism condition.
The main perpetrator of "Ka Makuakane" was a grieving father who simply wanted justice for his daughter. His two-year old daughter was killed in a car accident because the car seat she was on was faulty and it wasn't able to save her from being killed on impact. He was later told by the designer of the car seat that the company knew the the seat had a flaw but still put it on market and forced the designer to be quiet about the design flaw by paying him off. He eventually decided to kidnap the company owners' daughter to get back at them but end up grabbing the wrong girl in the process. He eventually orders the mother of the child to do the ransom demand who he blames mostly for the accident and he wanted to kill her but couldn't bring himself to and eventually surrenders and reveal the location of the girl.
Hoʻomaʻike. A guy is horrendously bullied in high school, culminating in being strung up like the victims in a recent slasher flick and being told he'll be killed if he ever tells. 20-some years later, the man's son murders the bullies the same way and then strings up his father and blames him for being weak. Not only is this poor man having to relive the worst moment of his life, it's at the hands of his own son.
In "Ua Hala" and "La O Na Makuahine," Chin Ho's overall Happy Ending Override courtesy of a vengeful Frank Delano.