Fallout 76 players who choose not to wait until NPCs arrive officially use hacking software to make their own.
When the Wastelanders expansion of Fallout 76 releases next year, it will bring to the desolate world of the game the first confirmed human NPCs.

It is not entirely accurate to say that human NPCs do not exist in the world of Fallout 76. Players discovered an NPC hidden in a dev room. Wooby, the human NPC, along with every other item in the game world, was found in the same place. Obviously, this room was not intended to be accessed by players.

Nearly a year later, thanks to an unofficial series of item spawning scripts, Wooby found a new life. A group called Dupers R Us used these methods not only to set Wooby free but also to incorporate and build their own NPCs from other games like Fallout 4.

“Their functionality is actually incredibly high,” Dupers R Us member Thegeminaii told Kotaku about NPC AI. “They will wander around your camp while idle, and in combat they will relentlessly chase their opponent, taking cover and retreating when necessary.”

However, as they point out, these NPCs don't have all the features you'd just expect. And all spawn with just their underwear for some reason.

Of course, there are other uses for the same cheats. Others used them to spawn in Fallout 4's Prydwen's Brotherhood of Steel's airship. Some used it to spawn NPCs like Preston Garvey, and Brotherhood of Steel soldiers.

Of course, none of this is official, but just like Prydwen, don't be shocked to see in your game a random NPC appear.