Mr. Lawrence. Actor: SpongeBob SquarePants. Douglas Lawrence Osowski (born January 1, 1969), known professionally as Mr. Lawrence, is an American voice actor, writer, and animator. He is best known for his work on the Nickelodeon TV series SpongeBob SquarePants (1999), in which he voices the character Plankton (among others) and has also co-written numerous episodes of the show. His other work includes voicing Filburt Turtle in Rocko's Modern Life (1993),...