It is very difficult to predict what will happen next on Game of Thrones. The plot is very unpredictable and most of the scenes happen unexpectedly. This includes even the death of the characters, whether a major character or a minor character, we did not expect them to die or we even did not expect how they die. So here's my list of the most devastating death in the series. This might not be everything but for sure many will agree with me.
1. Rob, Talisa and Caitlyn Stark
They are assassinated by the House Frey at the Red Wedding. Everybody thinks that Rob will be the one to revenge his father’s death but this happened to them.
Rob was promised to marry a daughter of Walder Frey but he fell in love with Talisa. This made Walder very upset so he wanted the Starks to pay for the promise they broke. Talisa was then carrying their child when they die.
2. Joffrey Baratheon
I really hate his character so much that death by poison in not yet enough for his. I was actually waiting for a more brutal death for him. Maybe to be skinned alive or chopped into pieces.
Hodor simply held the door so Bran Stark can escape the White Walkers.
4. Margaery and Loras Tyrell
High Sparrow and his followers gathered at The Great Sept for Cersei's trial but she blew up The Great Sept with wildfire killing everyone inside including Margaery and Loras Tyrell and their father Mace Tyrell.
5. Lady Olenna Tyrell
After the death of Mace, Margaery and Loras, Lady Olenna was very devastated that she made an alliance with Daenerys against Cersei. But the Lannister army conquered High Garden and Jaime gave poison to Lady Olenna. But before she dies, she told Jaime to “tell Cersei it was me.”
6. Renly Baratheon
Renly was the younger brother of King Robert and first husband of Margaery Tyrell. He is also the lover of Loras Tyrell. He was killed by a shadow created by Melisandre and I find that very nonsense. He could have a more meaningful death. Or maybe not to die at all so we can expect more Renly-Loras scenes.
7. Myrcella Baratheon
She is Cersei’s only daughter promised to marry a Dorne prince Trystane. She was poisoned by Ellaria Sand as a revenge for the death of Oberyn Martell. She plays a minor character but she doesn't deserve to die.
8. Ned Stark
After King Robert’s death, Cersei doesn't want Ned to be in King's Landing and to be hand to the king so she asked Joffrey to order beheading of Ned for treason. His death becomes a game changer for everyone and that was the start of the fall of House Stark.
There are so many characters in the story died but I think these are the most devastating deaths. Maybe they don't deserve to die but they are already dead now. Let's wait who will die next and how will they die.