Abstract: Methods and systems for idling a hydrocracker are provided. The method can include hydrocracking a hydrocarbon in the presence of a catalyst and hydrogen in a reactor to produce a hydrocracked product. A kill agent can be introduced to the reactor in an amount sufficient to reduce hydrocracking by at least 10% therein. In some examples, the kill agent can include one or more nitrogen-containing compounds, such as ammonia, amines, anilines, ammonia-containing compounds, amine-containing compounds, or, aniline-containing compounds. In some examples, the catalyst can include one or more Group VIII metals (e.g., cobalt, nickel, palladium, iron, alloys thereof), one or more Group VIB metals (e.g., molybdenum, tungsten, alloys thereof, or oxides thereof), and a catalyst support, such as a zeolite.