It is assumed that Mr. Gilbert spent most of his life living in Atlanta. It is possible that he was a religious man, as he can be seen wearing a cross necklace in "Vatos". He is now an elderly man who lives in a nursing home and is being taken care of by the nurses and Felipe. He also spends time with the nursing home's other residents such as Abuela. When the outbreak occurred, the nursing home staff abandon him and other residents, leaving them in the care of Felipe, Guillermo, and the other Vatos gang members.
While Rick Grimes, T-Dog, and Daryl Dixon stand-off in a confrontation with Guillermo and his men over Miguel, Glenn Rhee, and the bag of guns, Abuela rushes out in search for Felipe, worried for Mr. Gilbert, who needs his inhaler. He has began to suffer an asthma attack.
Rick follows Felipe and Abuela to the nursing home where he sees the elderly being cared for and sees a group of people trying to comfort Mr. Gilbert and help him with his breathing. The old man receives an inhaler and recovers from his asthma attack. His current status is unknown.
This list shows the victims Mr. Gilbert has killed:
- Possibly a few zombies
- "Vatos" (No Lines)