WARNING: The following article contains major spoilers for "Rick Grimes 2000" from Skybound X #1-3, on sale now.
In The Walking Dead comics and on the TV series, the Governor was a nasty villain and a despicable murderer. In the comics, he cuts a more twisted figure, though, leading the charge against the prison, instigating the riot that would kill many key players in Rick Grimes' camp. It culminated in Lori get shot through the stomach, with baby Judith dying and a bullet in Hershel's head.
While the Governor was subsequently killed in The Walking Dead #48, one of his soldiers, Lilly, got to do it, sickened by what he did to Lori and Judith. However, that took away the honor of killing him from one of the franchise's heroes. However, Skybound X #3 rectifies that in "Rick Grimes 2000" by giving the Governor a brutal and unforgiving death at the hands of one of Rick's closest allies, Andrea.
In this alien-filled alternate reality, the Governor is alive and well, getting cybernetic implants to become more dangerous than ever by working with the aliens who unleashed the zombie plague to thin out Earth'spopulation. He's got a cybernetically-enhanced Lori as a servant as well, and they're holding Rick hostage as they want him to join their alien overlords. Unfortunately, Lori is killed by one of the bosses, only for Andrea to enter the fray and murder that alien to save Rick. While Lori is gone for good, Andrea has hope she can repair Rick and potentially the beheaded Michonne using nanites she stole to fortify her army back at the Sanctuary.
Shocked from the bloody turns of events, the Governor pleads for his life and tries to switch sides. He says he has secrets Andrea's resistance can use but she doesn't care. She's got tech, resources and faith they can rebel without trusting someone like the Governor. As such, she blows his head to bits, ensuring he can't be resurrected by the aliens.
Even though Rick isn't the one who pulls the trigger, the fact that one of his closest allies got to kill the Governor is still fitting. Since he and Carl had to run away before they could see justice enacted in the main comic, seeing Andrea get her vengeance fits just fine, since she was also friends with Hershel.
The encounter also serves as a reminder to Rick of how much of a warrior she is and makes her stand out as the person to lead them into a new era in the future against a legion way more monstrous than the walkers.