Dennis the Gardener (surname unknown), more commonly known as "Dungo" or "Dungo Dennis", is an unseen yet pivotal character in the Red Dwarf universe.
Around the mid-22nd Century, Dungo was employed to maintain the botanical gardens of the Rimmer family home on Io. Mrs. Rimmer was known to be quite promiscuous and had numerous affiars, and Dungo was one of her many lovers. In 2149, Arnold Rimmer was born to Dungo and Mrs. Rimmer. Although Mr. Rimmer seemed aware of the fact, he raised Arnold as his own, but always with a resentment not far from the surface. As a boy, Arnold remembered Dungo as a "babbling imbecile".
Three million years later, Arnold Rimmer learned from a holo-lamp recording that the man he believed was his father was not, and in fact his biological father is in fact Dungo. ("The Beginning", Series X)
Dungo was an ordinary, working class man who was employed by the Rimmer family to look after their extensive gardens on the moon of Io. His nickname was not flattering, perhaps given because of his profession (dung as fertilizer) or personal hygiene. Arnold Rimmer had memories from his youth of Dungo as a "babbling imbecile". Mr. Rimmer stated that, unlike his own heritage of high-flying officers in the Space Corps and French and Austrian royalty, Dungo's lineage was that of "lame-brain artisans and pram faced trollops".
Dungo was one of the many lovers of Rimmer's mother, something of which Mr. Rimmer was aware. Dungo fathered at least one of her children - the youngest boy, Arnold. It is possible that one or more of Arnold's brothers were also his children, although Mrs. Rimmer was having affairs with Porky Roebuck's father ("Queeg"), her brother-in-law Frank, and several other men. Arnold once mentioned that The Boys from the Dwarf could have his mother, since "Everyone else did" ("The Last Day").
- In the booklet accompanying the DVD of Series III, it was suggested that Arnold's maternal brothers John, Frank and Howard were actually the sons of the man they called Uncle Frank.
Mr. Rimmer knew Arnold was Dungo's child, perhaps explaining his obvious disdain for Arnold during his childhood. His family kept Arnold's true parentage from him, making him grow up in an unhappy home trying to live up to the family's lofty ideals and military past. He eventually divorced them and joined the Space Corps. Arnold never knew that Dungo was his father until much later in life, and as a youth Arnold and Dungo apparently were not close, with Arnold referring to him in a derogatory sense.
When he believed that he and his shipmates were about to be slaughtered by a Simulant Death Ship and that he would never achieve his dreams of success, Arnold decided to follow the Cat's advice to exorcise his father's disapproval. He decided to watch a holo-recording that he had been told to watch only when he had been given an officer's commission, reasoning that doing this would reflect his having moved beyond his father's expectations of him and could move on from trying to fulfill his father's ideals. In the holo-recording, Mr Rimmer proceeded to tell Arnold that he was not his biological father, who was actually Dungo Dennis, the "imbecile". Dave Lister commented that it was a billion-piece jigsaw puzzle coming together.
Mr. Rimmer informed Arnold of his true parentage and told him that he would receive no more birthday presents. Despite the revelation of his illegitimate status and lowly pedigree, Arnold was encouraged by this news. He had thus achieved everything by himself without help from Mr Rimmer. By his social father's standards, Arnold was a miserable failure and disappointment, but to Dungo he would be a terrific success. Dungo was a simple man who would take Arnold's exploits in space and low rank to be wonderful achievements. Psychologically freed of Mr. Rimmer, Arnold began to think of himself as a working class hero and managed to come up with a plan using the Molecular Destabilizer to save the Dwarfers from destruction. (RD: The Beginning)
Behind the scenes
When we saw Arnold hanging upside-down from a tree in the family garden during the episode "Dimension Jump", the gardens were presumably the work of Dungo. Not to mention, given his mother showed very little interest, it might well have been Dungo who untied him.