Most popular fire-type users of all time.

 They are the most popular Fire-Type characters in anime. 

 1. Genryusai Shigekuni Yamamoto(Bleach)

Genryūsai Shigekuni Yamamoto (山本元柳斎 重國, Yamamoto Genryūsai Shigekuni) is the captain of the 1st Division and Captain-Commander (Head-Captain in the English Dub) of all "The Divisions" , later known as the Gotei 13, as well as the "Genryū" Founder and "Genji School" Head Instructor.  One of the most powerfull shinigami to be ever appeared in Soul Society having thousands of years of battle experience. His sword has two unique form ,"shikai" and "bankai". In his bankai form flames cover his blade and himself.  No one can touch Yamamato during the Bankai. as temperature of his flames reach around 15,000,000 Degrees, and while using this Yamamoto calls himself the embodiment of the sun. It is said that if he remains in this state for long time , the surface of earth will start getting melt. 

2. ACE ( One Piece)

Ace, born as Gol D. Ace and nicknamed "Fire Fist" Ace, was the sworn older brother of Luffy and Sabo, and the son of the late Pirate King, Gol D. Roger and his lover, Portgas D. Rouge. Ace was adopted by Monkey D Garp as promised. Ace and luffy grew up together. Garp want them to become great MARINES but they were only interested being Pirate. Ace was taken up by whitebeard and was given a rank of 2nd devision commander in Whitebeard Pirates( shirohige kaizokudan). He ate flare flare devil fruit(Mera Mera no mi) , a logia type devil fruit which enables the user to take over fire element as thier devil friut power. He was one of the most powerfull pirate in Whitebeard's ship. Ace was killed by the current fleet admiral Sakazuki ( akainu ) while saving Luffy. 

3. Natsu Dragneel ( Fairy Tail) 

Natsu "Salamander" Dragneel  is depicted throughout the story as a member of the eponymous wizards' guild, who are notorious in the fictional kingdom of Fiore for their numerous accounts of causing unintentional property damage with their magic. Being a Dragon Slayer , Natsu possesses the same abilities as his foster father, the dragon Igneel, namely the ability to consume and envelop himself in fire. Natsu's predominant role in the series is to reunite with Igneel, who has been missing for seven years by the story's outset. Over the course of the series, Natsu learns about his connection to the immortal antagonist Zeref, including his heritage as Zeref's brother who was revived as a demon called "Etherious Natsu Dragneel" (E.N.D.).  

Fire Dragon King Mode: Natsu's strongest form, Fire Dragon King Mode was granted to Natsu by Igneel, giving him Igneel's magical power. In this state, Natsu is capable of killing Zeref, the strongest dark wizard in the series. 

4. Roy Mustang ( Fullmetal alchemist: brotherhood)

Roy Mustang (ロイ・マスタング Roi Masutangu?), also known as the Flame Alchemist (焔の錬金術師 Honō no Renkinjutsushi?), is the tritagonist of the Fullmetal Alchemist series. He is a State Alchemist and officer in the Amestrian State Military. A hero of the Ishval Civil War and Edward Elric’s superior officer, Colonel Mustang is a remarkably capable commander who plans to become the next Führer of Amestris. Being one of the most powerfull alchemist in the whole series , he uses fire alchemy which is very powerfull technique which even killed high speed body generating homunculus( nearly immortal ).

5. Alibaba Saluja ( Magi)

Alibaba Saluja (アリババ・サルージャ Aribaba Sarūja) is the former third Prince of the Balbadd Kingdom. He was working as a cart driver when he first met Aladdin. He was the co-leader of the Fog Troupe. Being a Dungeon Capturer, he is the owner of the Djinn Amon and Aladdin's King Vessel. Before the Kou Empire Civil War occurred, Alibaba was killed by Hakuryuu, and his consciousness was sent by Belial to a dimension where time moves slowly. He comes back to life with the help of the magicians from Alma Torran to prevent the destruction of their world. He is the deuteragonist of the series Magi.