Well, people, actually. 60-70 men and women (Quakerism being one of the more egalitarian sects) who were converted to Quakerism at an early stage in its development. They were active between 1647 and 1660 and, following the example of George Fox, dedicated themselves to spreading Quakerism throughout the England. They included James Nayler and Francis Howgill, who had both independently developed beliefs similar to the Quakers before hearing about Fox.
As itinerant preachers, their main aim was conversion, not establishing a church. They tended to target already-established separatist groups, so that they could convert many at once and have a pre-establised network of groups throughout the country. Also, the separatist religious groups, by definition, had already embraced religious radicalism, and so were probably easier to convert; many would already hold beliefs similar to those of Fox and the First Publishers of the Truth.
These early evangelists were instrumental in the spreading of Quakerism throughout the country. The groups they established contributed to the Quakers' organised structure, and therefore helped them to survive the persecution following the Restoration and the Glorious Revolution. Sadly, constant travelling, beatings and frequent imprisonments were occupational hazards, and many of these early Quakers died young.