I'd say characters like Harry Potter had their fair share of suffering. Losing his parents at a young age and constantly facing life-threatening dangers was tough.
Jotaro Kujo is very memorable. His cool and stoic personality, along with his powerful stand Star Platinum, makes him stand out. He has some great fight scenes and his journey to defeat Dio is really engaging.
In 'Shiki', Sunako Kirishiki is a key vampire character. She is the one who starts the vampire epidemic in the village. Her character is both alluring and terrifying as she tries to find a way for the vampires to coexist with the humans in the village, but her methods are often cruel.
I would say Anti - Mage is also very popular. His story of seeking revenge against the mages is quite appealing, and his in - game abilities are very strong in the anime story too.
Edward Elric from 'Fullmetal Alchemist' also has a great story. He and his brother Alphonse, in an attempt to bring their mother back through alchemy, violated the taboo and lost parts of their bodies. Edward then embarked on a journey to find the Philosopher's Stone to restore their bodies. His story is full of themes like sacrifice, redemption, and the pursuit of knowledge.
Definitely Naruto. He's the main character, and his journey from a nobody to a hero is inspiring. Sakura Haruno is memorable too. She starts as a girl with a crush on Sasuke but grows into a strong kunoichi. Rock Lee is also a great character. He can't use ninjutsu or genjutsu but through sheer hard work in taijutsu, he becomes very powerful. His green jumpsuit and bushy eyebrows are quite the trademark.
Eren Yeager is extremely important. He's the main protagonist and his journey from a young boy seeking revenge against the Titans to a key figure in the fight is central to the story. Mikasa Ackerman is also important. She's a highly skilled fighter and has a deep bond with Eren. Levi Ackerman is another crucial character. He's known for his incredible combat skills and leadership within the Survey Corps.
Blue is also quite popular. In fanfiction, his rivalry with Red can be intensified or even given a new twist. Maybe they have to team up against a greater threat, which makes for some really engaging character dynamics as they put aside their differences.
Tohru Honda is very memorable. She is kind - hearted, optimistic, and has a big impact on the Sohma family. Her ability to see the good in everyone makes her stand out. Kyo Sohma is also memorable. His struggle with the family curse and his relationship with Tohru are central to the story.
In 'Sailor Moon', Sailor Moon herself, Usagi Tsukino, is extremely iconic. Her transformation sequences and her growth throughout the series are memorable. In 'Madoka Magica', Madoka Kaname is iconic for her role in changing the very nature of the magical girl world. Also, Sakura Kinomoto from 'Cardcaptor Sakura' is well - known for her cute and determined personality.