Charles Steen was a disgruntled person who tried to obtain money from Audrey Geisel, the widow of the late Theodore Geisel aka Dr. Seuss. Steen emailed Geisel asking for $2.5 million after taxes, or "I'll do something you'll regret".
Steen lost a plagarism case against Dr. Seuss in 2001 over a book Seuss wrote called "Daizy-Head Mayzie" claiming Seuss plagarized his childrens book "The Pains of Being True at Heart".
That's when the threats to Audrey Geisel started. Steen threatened to go public with paintings of Seuss's characters in sexually compromising positions. Steen was arrested, sentenced to three months probation, counseling, and no contact with Geisel. Source