Question: While working on "The Lord of the Rings", Greg Butler worked on the effects for a fictional character first imagined by what famous author?

 He was introduced in the 1937 fantasy novel "The Hobbit", and became an important supporting character in its sequel, "The Lord of the Rings".  Gollum was a Stoor Hobbit of the River-folk, who lived near the Gladden Fields. Gollum is a fictional character from J. R. R. Tolkien's legendarium.  Originally known as Sméagol, he was corrupted by the One Ring and later named Gollum after his habit of making "a horrible swallowing noise in his throat". <SEP> Dori Hillestad Butler (born August 26, 1965) is an American author of children's books.  She has written more than 40 children's books, as well as magazine stories, plays and educational materials.  She is known particularly for "The Truth about Truman School", a 2008 young adult title focusing on the subject of cyber bullying, and for My Mom's Having a Baby (illustrated by Carol Thompson), which in 2011 appeared on the American Library Association's list of most challenged books for its portrayal of conception and childbirth.  Her 2010 mystery title, "Buddy Files: Case of the Last Boy", won the 2011 Edgar Award for the best juvenile mystery published in 2010.  Prior to becoming a children's author, Butler worked for three years as a page at a library.  She is married with two sons.  The family lives in Kirkland, Washington. <SEP> Aragorn II, son of Arathorn is a fictional character from J. R. R. Tolkien's legendarium.  He is one of the main protagonists of "The Lord of the Rings".  Aragorn was a Ranger of the North, first introduced with the name Strider at Bree, as the Hobbits continued to call him throughout "The Lord of the Rings".  He was eventually discovered to be the heir of Isildur and rightful claimant to the thrones of Arnor and Gondor.  He was also a confidant of Gandalf and an integral part of the quest to destroy the One Ring and defeat the Dark Lord Sauron. <SEP> Gregory S. Butler (August 18, 1971, Suffield, Connecticut) is a visual effects supervisor.  He graduated from Suffield High School in 1989 and afterwards entered Hampshire College.  While reluctant at the requirement of moving to New Zealand, Butler was convinced by his writer-actor brother Jared to jump at the opportunity of working for Weta Digital in "The Lord of the Rings".  Despite his initial plans to study history, a work-study job with the audiovisual equipment in the library made him interested in film production.  Butler graduated in 1993 with a major in film, television and theater design.  Afterwards he moved to California to work for Industrial Light and Magic for 9 months, where after intern work he managed to become an assistant in the effects department, starting with assistant credits in "The Mask" and "Forrest Gump".  Following a job at Rocket Science Games until the company's bankruptcy in 1996, Butler went to Tippett Studio and did effects work in "Starship Troopers" and "My Favorite Martian", rising up to a technical director job, and Cinesite for "Practical Magic".  His biggest achievement was working in the creation of Gollum.  Butler also worked as a computer graphics supervisor on "I, Robot" before an invitation to work as an effects supervisor for the Moving Picture Company, in London.  He continues on MPC, but is now on the Vancouver office.  On January 24, 2012, he was nominated for an Academy Award for "".