As soon as I saw the character in a cutscene of GTAV I noticed he seems to be a 'nerd' with glasses. And he somewhat talks like somebody I've seen in previous GTA games. I've thought to myself "is that meant to be Zero from grand theft auto san andreas?". I've been online and searched for the answer, but I found nothing, so if anyone has sources or know the answer could I please know?...It's really bugging me.
Rockstar has addressed this before. Check the Other Characters section of this GTA III Q&A.
El Burro is referenced as he was also referenced in GTA 1, so it felt appropriate that he should cross “universes” – the “universes” are the worlds interpreted at different definitions, 2d, 3d and high definition, so we felt brands and radio / back ground characters would exist in both, but 3 dimensional characters would not. This is the logic (as far as it could be considered logical) behind it – so no, we don’t believe any GTA3 characters could exist in the GTA4 universe.
As the quote says, the GTA series has been rebooted twice.
2D Universe: GTA/GTA London (1969/1961)/GTA 2
3D Universe: GTA III/Vice City/San Andreas/Advance/Liberty City Stories/Vice City Stories
HD Universe: GTA IV/Episodes from Liberty City/Chinatown Wars/GTA V/Online
Zero is a 3D Universe character, and Lester is an HD Universe character. They don't exist in each other's universes, so they're not the same person.
I think it's possible, even if they're in different, "universes." I think at least it should be noticed that they're into the same things, both like anonymity, similar voices, both wear glasses, same race and hair color.
Being that San Andreas is set in the 90s and GTA V set in more modern times, Lester could be an older Zero.
Rockstar says that brands and background characters share universes, such as Lazlow who is a radio personality we hear on in III-San Andreas. We finally meet him in person in GTA V. The thing that should be defined is what exactly counts as a, "background," character in the instance of Rockstar's explanation. I think there is a possibility that Lester and Zero are one and the same, even with comments from Rockstar possibly saying otherwise.
I definitely believe Lester is actually Zero for many reasons, starting with that they are both exactly similar. GTA SA was set in the 80s and features a young Zero (who doesnt actually have a real name) whereas Lester in GTA 5 (set in today) features a character which would suit the age. Lester could also have changed his name for security reasons, especially as Zero aids and talks you through your first big heist in GTA SA, EXTREMELY similar to Lester... Too similar