How often are characters reused between gta online and story mode?

In GTA V, the primary playable characters Michael De Santa, Franklin Clinton, and Trevor Philips serve as the main protagonists of the story mode. In GTA Online, these same three characters are available as playable avatars that players can choose to represent themselves in the shared world. Aside from these lead characters, a number of supporting NPCs from the single‑player narrative—such as Trevor’s crew members, Franklin’s gang, and various other recurring figures—appear as non‑player characters in online missions, side‑jobs, or as part of the world’s background. However, the majority of the story‑mode characters are not playable in the online mode, and many of the deeper, plot‑specific characters do not reappear in GTA Online. Thus, while there is a notable overlap, it is limited mainly to the three protagonists and a handful of key NPCs.