A famous
Jewish Rabbi. He lived from about 70 B.C.E. to about 10 A.D.
Hillel is known for teaching the Spirit of the Law, a more lenient school of Jewish thought, and is contrasted with Shamai (or Shemaiah), who taught the letter of the Law. Hillel's most famous line reflects his interpretation of the law of the Torah: "Do not unto thy neighbour that which you would not have him do unto you. This is the whole Jewish law. All else the rest is but commentary." (Or "What is hateful to you, do not do to your neighbour. That is the whole Torah"). (More here)
He was born in Babylonia, but in his thirties traveled to Jerusalem to study under Shemaiah and Abtalion. He learned well, and around 30 B.C.E. he became Nasi (president of the Sanhedrin). King Herod was the ruler of Palestine at the time, but the people viewed him as a tyrant. They looked to Hillel, and later his to his descendants, as the spiritual leader of Palestine. Matters were helped by the fact that Hillel was a descendant of King David. He had quite a lot of power in this role.
Hillel (subtitled "The Foundation for Jewish Campus Life") is now the name for a organization that encourages Jewish students to be active in their faith during their college years. Their mission statement seems to be to maximize the number of Jews doing Jewish with other Jews.
Partial references:
http://www.ivanlewis.com/History/hillel.html (Has some good stories from Hillel's life)
http://www.hillel.org/hillel/newhille.nsf/Home%20Page?OpenPage (For the organization)
http://www.newadvent.org/cathen/07354c.htm
etc.