who is luffy's grandfather

As of now, in the manga, the identity of Luffy's mom remains unknown. There have been many theories and speculations among fans, but no official confirmation.

There could be an original character created just for the fanfiction. A woman with a kind heart but a tough exterior, who was a great fighter. She could have met Luffy's father during a battle and they fell in love, and she became Luffy's mother.

Di Renjie's grandfather was Di Xiaoxu.

Di Renjie's grandfather was Di Xiaoxu.

Liu Bang's grandfather was Duke Feng, Liu Rong.

Liu Bang's grandfather was Liu Qing. Liu Qing was a doctor in Wei at the end of the Warring States Period. Later, he moved to Feng County and was buried in the ancestral tomb of the Han Emperor. Liu Qing was Liu Bang's grandfather, the origin of the Liu family.

Huo Jianhua's grandfather was Huo Weisi.

Fan Xian's grandfather was a secret. The novel did not reveal who Fan Xian's grandfather was. Thus, Fan Xian's grandfather's identity was unknown.

Fan Xian's grandfather was Xiao En.

Han Xue's grandfather was Han Shu.