William Bell is a successful businessman and former partner of Walter Bishop.  Their research together would eventually be the groundwork that Bell used to form Massive Dynamic, one of the world's foremost science and technology companies.  William Bell eventually becomes one of the wealthiest and most powerful men on Earth, but more recently he has become a recluse.

When Fringe Division start investigating the Pattern, they discover that William Bell is not just a recluse but has actually gone missing.  Even Nina Sharp, Executive Director of Massive Dynamic, has been out of contact with the CEO and is unaware of his location.  When Bell finally does make contact with Olivia, it only leads to more questions.  It also led to one of the series's greatest guest stars, Leonard Nimoy.