Grelb functioned as the delivery person for Jemba the Hutt.
In the year 44 BBY, Grelb found himself working for Jemba, the Hutt, and was stationed aboard the Monument. He was traveling with Offworld Mining Corporation employees on a voyage to the planet of Bandomeer. Following an assault on the Monument by Togorian pirates, the vessel was forced to execute an unplanned landing on an island situated on an unknown planet that possessed five moons.
After the ship had to be abandoned due to rising floodwaters, Grelb received instructions to safeguard the pilfered dactyl. He followed these orders until he became wary of Qui-Gon Jinn (who was also on his way to Bandomeer), noticing that the Jedi was taking a different route than the rest of the crew. He commanded the Whiphid thugs to eliminate the Jedi, but their actions instead attracted the attention of the native draigons. When Jemba's thugs were devoured by these flying reptiles, Grelb fled as the draigons began their assault on Qui-Gon Jinn and the remaining passengers. Fearing retribution from his boss, he began plotting to murder the Jedi. However, before he could strike, Qui-Gon vanished into the caves along with the recovered dactyl. Enraged, Grelb turned his attention to Jinn's apprentice, secretly admiring Obi-Wan's abilities and almost regretting the need to kill him. Obi-Wan managed to evade a stray blaster shot, which ironically struck and killed Jemba, who was also attempting to assassinate the Jedi. Before he could get away, Grelb was attacked and consumed by a draigon.