Logo used at the end of the 1997 SpongeBob SquarePants pilot. This logo only conists of the words "Created by Stephen Hillenburg" and a drawing of SpongeBob. This was made before United Plankton Pictures was officially formed on April 1, 1998.
United Plankton Pictures, Inc.
United Plankton Pictures was created on April 1, 1998, but they did not start using a proper on-screen until 1999.