Winry would be heartbroken. She loves Edward deeply. She might initially go into denial and then be filled with anger at the circumstances that led to his death. She could also turn her grief into a determination to help others with her mechanical skills, in memory of Edward.
Roy Mustang would be furious. He sees Edward as a valuable ally and a young person with great potential. His death would make Roy more determined to clean up the military and the world that allowed such a thing to happen. He might also feel a sense of guilt for not being able to protect Edward, especially since he's in a position of power in the military.
Sasuke would be deeply affected. He and Naruto had a complex relationship. He might feel a sense of regret for all the times he had pushed Naruto away. His reaction could range from anger at the situation to a new - found respect for Naruto's sacrifice.
Hermione would likely be devastated. She might go into a deep state of mourning, but also use her intelligence to try and figure out what led to Harry's death. Ron would be angry and heartbroken at the same time. He'd probably want to seek revenge if there was someone or something responsible.
Alphonse would be very protective. He'd probably be constantly worried about his baby brother's safety. He might be a bit clumsy at first with taking care of a baby, but his determination would make him learn quickly.
The characters would be devastated. Kurt, being one of her closest friends, would probably be in shock at first. He might go through a period of denial, thinking it's all a cruel joke. Then he would break down and cry, remembering all the times they shared together, from their fashion debates to their duets. He would likely be the one to organize a proper memorial for her, making sure it was as grand as Rachel would have wanted.
Naruto would be extremely devastated. He sees Kakashi as a mentor and father figure. He might go into a period of deep depression at first, but then turn his grief into motivation to become stronger. Sakura would also be very sad and might focus more on her medical skills, vowing to save more lives in Kakashi's memory. Sasuke might have a more internal reaction, feeling guilty if Kakashi died protecting him, and it could further fuel his own goals, whatever they may be at that time.
Lucy would be completely devastated. She and Natsu have a very close bond. She might go into a deep depression, constantly blaming herself for not being able to save him. Gray would be angry at first, feeling like he should have been there to help Natsu. Then he'd be sad and would probably vow to avenge Natsu. Erza would be strong on the outside but inside she'd be broken. She might try to keep Fairy Tail together in Natsu's memory. Happy would be inconsolable, constantly flying around looking for Natsu and refusing to believe he's really gone.
Well, some characters' reactions can be really complex. For example, Dumbledore's portrait might show a solemn look, as if he knew this was an inevitable outcome. The students at Hogwarts would be in a state of shock. Those who were in Slytherin house might feel a sense of loss for their head of house, even if they didn't always understand him. And Neville, he might see Snape's death as a tragic end to a misunderstood hero.
The other members of Team RWBY would be deeply affected. They would start to question their own abilities and the purpose of their fight. Some might withdraw into themselves, like a broken Weiss who shuts out the world for a while. Yang, on the other hand, could become reckless in her pursuit of vengeance, endangering herself and others. Blake would try to hold the team together, but she would also be mourning privately. The other friends and allies in the RWBY universe would also be in mourning. Qrow might blame himself for not being there to protect Ruby, and Ozpin would see it as a great setback in the fight against evil.
The Weasley family would also be greatly affected. Mrs. Weasley would surely mourn Harry as one of her own. Ginny, who had feelings for Harry, would be heartbroken. She might become more fierce in her pursuit of justice in the wizarding world. And the other students at Hogwarts, like Neville, would be inspired by Harry's sacrifice to step up and be braver in the face of danger.
Alphonse Elric is often present. He might play a role in helping Edward understand and use his new gamer - like abilities in relation to alchemy. For example, he could be the one who discovers a new aspect of Edward's powers.