Chimeji elPrahno was a male Payav of the Nehdi tribe on planet Mestiko in the 23rd century. He was the grandson of Nehdi leader Ejo elPrahno and his wife, Sorodel. Chimeji's parents died in 2293 of a mysterious illness, leaving him to be raised by his grandparents.

Chimeji befriended Dr. Leonard McCoy when he came to the Nehdi Valley to investigate the deaths there, and assisted him with simple tasks in his lab. McCoy gave the boy the nickname "Chimmy".

Chimeji was also responsible for finding several dormant noggik seeds unearthed by a construction project near his home, the first to have been discovered since the destruction of "the Pulse". (TOS eBook: Its Hour Come Round)

While an actual age for Chimeji is not given, he is described as being about seven or eight years old in human terms.