original investors would include a broad group of people: venture capitalists would be one.  Private investors another.  the time and money of the entrepreneur would be another.  in most cases I'm involved with, the entrepreneur has his family and friends involved.  then if the company looks good, and meets milestones, other investors will get in the following investment rounds, and might include other financial investors, like banks and funds focused on "mezanine" type financing.  the previousl list is not exclusive, there might be others--pension funds, for example.