There are fifteen special characters that are available. The first to appear is Ronald Chump. Art Major will be the first one to show up for your lobby. To unlock these characters, build new floors that correspond with the character. For example, to unlock Sergeant Garza build a Security Block Floor. Keep VIPs waiting in the lobby. Job applicants are plentiful, but VIPs are a rare occurrence. Keep a few of them in your lobby ready to be used when you needed. Also make sure that your lobby is not full to allow for more VIPs to appear.