Glenn Rhee/Season 1

During one of his missions, Glenn led a group of volunteers from the camp into the city for supplies, although he did it reluctantly since he preferred to work alone. Later that day, gunshots had alerted walkers to their location, and the group was forced to hide inside a department store. After watching how Rick Grimes hid in a tank to escape from a herd of walkers, Glenn managed to contact him through the tank radio. ("Days Gone Bye")

Having provided him with instructions on where to run, Glenn helped Rick escape alive from his perilous situation and, after making sure they were both safe, took him to his refuge where the rest of the group was waiting for them. Shortly after Rick restored calm by handcuffing Merle Dixon to a pipe on the roof, Glenn began to respect and admire the newcomer and helped him devise a plan to escape from the building. When Glenn and Morales were unsuccessful in finding an exit through the sewers, the group was forced to come up with another plan.

Using the guts of one of the undead to camouflage their scent, Glenn and Rick were able to move among the horde roaming the streets and get a vehicle for the group to escape. Upon realizing that they also needed a distraction to lead the walkers away from the store, Glenn volunteered to drive a sports car and the group escaped, although they were forced to leave a handcuffed Merle behind. Once the plan worked, Glenn continued driving his new vehicle with excitement while leaving the city. ("Guts")

Glenn was the first of the group to arrive back at the camp and informed everyone that a new survivor helped them escape from the city, only to be surprised to learn that Lori and Carl were the family members that Rick was looking for. The next day, his happiness for his new acquisition did not last long since Dale asked for parts of the vehicle to repair the RV's radiator hose. Later that day, Glenn was enlisted by Rick for his mission to return to the city to rescue Merle due to being the only one to know the layout of all the streets. When the rescue group arrived at the rooftop of the store in Atlanta, they only found Merle's severed hand. ("Tell It to the Frogs")

After following a trail of blood and discover that Merle had also escaped from the building somehow, the group decided to retrieve the bag of guns that Rick had dropped a day ago before they could continue searching for him. While carrying out their plan, another group of survivors, who had also taken an interest in the bag of guns, kidnapped Glenn and demanded the bag in exchange for his return. Following failed negotiations, Rick learned that the enemy group actually needed the weapons to protect some elders who had been left under their care, and that Glenn wasn't harmed at all, he decided to share half of the guns and ammo with them. Having partially completed their mission in the city, the group returned back to the camp that night to find it under attack from some walkers and then they quickly helped defend the place. ("Vatos")

The next morning, Glenn was still affected by the recent massacre as he helped collect all the bodies. When Daryl Dixon tried to burn them instead, Glenn reminded him that their companions deserved a proper burial as a sign of respect since it was the right thing to do, and not to be burned like they were going to do with the undead. The next day, Glenn was present in the last camp meeting where he said goodbye to the Morales family. While the remaining group of survivors departed towards the CDC, they left an infected Jim under a tree by the road as his last wish. Upon arriving at their destination, they found everything abandoned. As some walkers began to approach them, Glenn tried to convince Rick to leave when suddenly the doors opened in time. ("Wildfire")

Upon entering the CDC, Glenn and the others were reluctantly welcomed by the sole remaining employee, Dr. Edwin Jenner, who allowed them to stay in exchange for some blood tests. That night, the group had a feast in the cafeteria and enjoyed all the luxuries the facility had to offer, beyond happy about having found a safe place. Glenn enjoyed a lot of wine during the dinner and was mocked by Daryl for getting drunk very easily. Shortly after, Glenn had a hot shower and then a change of clothes. The next morning, Glenn and the group learned that the virus that had caused the outbreak erased any conscious human traits from someone infected.

When the power generators began to ran out of fuel, Jenner revealed that the facility would explode due to a self-destruct protocol and then sealed everyone inside the control room, explaining that it would be a quick and painless death. Glenn joined in the attempts to open the door. After Rick eventually made Jenner change his mind, the survivors ran in a hurry to escape. Upon finding the top doors locked, Carol handed Rick a grenade she had found in his uniform and everyone took cover as he used it to blast one of the windows. Glenn and the group escaped as the CDC exploded and then continued their journey towards a new destination. ("TS-19")