- "It's the same as it ever was. The weak get taken. So we do what we can here. The Vatos work on those cars, talk about getting the old people out of the city. But most can't even get to the bathroom by themselves, still, it keeps the crew busy, and that's worth something. So we barred all the windows, welded all the doors shut except for one entrance. The Vatos, they go out, scavenge what they can to keep us going. We watch the perimeter night and day and we wait. The people here, they all look to me now. I don't even know why."
- —Guillermo to Rick Grimes and T-Dog about the apocalypse and the elderly[src]
Guillermo, also referred to as "G", is the head of the Vatos gang and the custodian of the nursing home in Atlanta, Georgia, as well as a survivor of AMC's The Walking Dead. He appears as a tough, no-nonsense thug, but only acts on best intentions for his people, which includes a handful of elderly and helpless folks. He is intelligent, and the Vatos gang trust and respect him.
Before the outbreak, Guillermo lived in Atlanta and was working as a custodian at the nursing home. He and a nurse named Felipe were friends and spent their days looking after the elderly in the nursing home. However, once the outbreak occurred and people began turning into walkers, all the other nurses and doctors ran away, abandoning the seniors and leaving them to die. Guillermo and Felipe decided to stay behind and take care of them.
Guillermo is mentioned by Miguel as the boss of the gang and takes Rick Grimes to him. Guillermo is well protected with a gang of tough-looking men. Guillermo has Glenn Rhee hostage, demanding for "his" bag of guns back, along with Miguel, otherwise Glenn would be killed, revealing Glenn to be tied up on the roof. He warns that Rick better come back, with his demands met, or "locked and loaded." Rick, T-Dog, and Daryl Dixon return, armed and ready for a fight. During this second encounter with the Vatos gang, an old woman trudges into the garage, calling Felipe for help. On seeing the armed newcomers, she warns them against harming Guillermo, who is a "good boy" and bids them to follow her when Rick tells her that they are just there for Glenn. Soon, Rick realizes that the building is filled with elderly patients. He pulls Guillermo aside and berates him for his behavior, saying that they weren't bluffing and were ready to kill. Guillermo echoes their commitment, saying that someone had to take care of these people after the nursing home staff abandoned them, leaving him, the head custodian, and Felipe, a nurse, behind. The rest of the gang members and some of the family members who came looking for their relatives stayed voluntarily to look after them as well. It seems Guillermo took charge and decided to watch out for his people and protect the food and medicine, and he saw that the guns would have been a good asset to the large group. Rick donates half of his guns and ammo before bidding farewell to Guillermo and his people.
This list shows the victims Guillermo has killed:
- Possibly numerous counts of zombies
Guillermo is the leader of the group residing in the Atlanta Nursing Home and is keeping Abuela, Mr. Gilbert, and the rest of the elderly people safe and well-supplied. When Rick, Daryl, and T-Dog go into the nursing home armed, Guillermo warns Felipe to move Abuela to safety, showing he at least cares about her well-being.
Felipe and Guillermo have had a good relationship as friends, since before the outbreak began, as they both looked after the nursing home. They were seen working together as a group with other members of Vatos gang while looking after the elderly in the nursing home.
- Originally, Neil Brown Jr. was just an extra, but the producers eventually decided the Nursing Home survivors needed a leader. 
- Guillermo was supposed to be an infected walker at the overrun nursing home. However, this scene was cut out of Season 2, leaving his official status as unknown.