Mark Jones, the writer-director, had a career in American television shows. Desiring to make a film, he decided that a low budget horror film was his best opportunity. Jones was inspired by the Lucky Charms commercials to create a leprechaun character, only his twist was to turn the character into an antagonist. Jones was further influenced by the film "Critters", which featured a small antagonist. Jones brought the concept to Trimark, who were looking to get into film production and distribution. "Leprechaun" became the first film produced in-house by Trimark to be theatrically released. "Entertainment Weekly" quoted the budget at "just under $1 million". In an interview with "Fangoria", Jones stated that he began writing the script in 1985 and spent a long time developing the Leprechaun character, which he initially envisioned as a "horrible, murderous creature", but which became a more comedic and developed character before filming began. Warwick Davis, who had experienced a dry spell after playing the protagonist in "Willow", liked the script and was excited to play against type. Jennifer Aniston, who was an unknown at the time, impressed Jones, and he fought to have her cast.