10 – Nico Robin
Luffy and Nico Robin first began as enemies, but after Robin saves his life in Alabasta, Luffy grows to trust her more deeply which he shows by allowing Robin to join his crew without any reluctance.
9 – Trafalgar D. Water Law
Trafalgar Law and his crew braved the Battle of Marineford and the attacks of the Marine admirals just to save Luffy.
8 – Vinsmoke Reiju
During their first meeting, Reiju noticed immediately that Luffy was slowly dying from the effects of consuming the Armored Stonefish’s poisonous skin. Unlike her younger brother Yonji, Reiju chose to save Luffy’s life, sucking the poison out of his body as her thanks for everything the Straw Hats had done for Sanji.
7 – Roronoa Zoro
At Thriller Bark, Zoro decided to give up his life to save Luffy from Bartholomew Kuma because he was ready to die for the dream of his captain. Kuma found this trust admirable as he was moved by Zoro’s compassion.
6 – Marco the Phoenix
After Ace’s demise, he stopped Akainu from killing Luffy and urged the other Whitebeard Pirates to save Luffy, as Ace sacrificed his life for his.
5 – Jinbe
While initially assisting Luffy only to protect and rescue Ace, Jinbe grew so fond of Luffy that he proclaimed while fighting Akainu at Marineford that he would gladly lay down his life to protect Luffy. It was Jinbe who also brought Luffy out of his self-pity and doubt. The fishman made Luffy realize that even though Ace had died, he still had his own pirate crew. After the battle of Fishman Island, in which Luffy lost a large amount of blood, Jinbe offered his blood for the transfusion.
4 – Monkey D. Dragon
Their only meeting was when Dragon rescued Luffy from being captured by Smoker in Loguetown.
3 – Mr. 2 Bon Kurei
Luffy became good friends with Bentham after he apologized for causing them trouble in Alabasta, and distracted the Marines so the Straw Hats could escape. Bon Kurei went as far as to give his life away to save Luffy and other Impel Down prisoners by posing as Magellan and ordering the opening of the Gates of Justice during the Impel Down Arc.
2 – Shanks
Shanks is the pirate who saved Luffy’s life twelve years ago in his hometown. He sacrificed his arm in order to save Luffy from the Sea King.
Shanks said he bet his arm for the future. He probably did this intentionally to show Luffy what it takes to become a pirate. Luffy had stated to him at a young age he wanted to be a pirate as great as Shanks and Shanks wanted to show him what it means to be a pirate and that means risking everything and possibly losing your arm or worse your life.
1 – Portgas D. Ace
Hunted by the World Government for his lineage, Ace was captured and sentenced to death, which resulted in the Battle of Marineford in an all out clash of powers. Ace was freed, but he sacrificed his life to protect his younger brother Luffy from Akainu.