Dr. Zachary Smith is a fictional character from the classic science fiction television series, Lost in Space. He is portrayed as a self-serving and often cowardly scientist who frequently finds himself in humorous and precarious situations. His character is known for his catchphrase, "Oh, the pain!" which reflects his tendency to exaggerate his misfortunes. In the series, Dr. Smith initially poses as a helpful member of the Robinson family, who are on a mission to colonize a distant planet. However, his true motives often lead to conflicts and challenges for the crew, making him a central figure in the show's dynamic.