Light My Fire was primarily written by Robby Krieger who wanted to write about one of the elements: fire, air, earth and water.
In an interview, he said "I was living with my parents in Pacific Palisades – I had my amp and SG. I asked Jim, what should I write about? He said, 'Something universal, which won't disappear two years from now. Something that people can interpret themselves.' I said to myself I'd write about the four elements; earth, air, fire, water, I picked fire, as I loved the Stones song, 'Play With Fire,' and that's how that came about." Krieger created the melody, and wrote most of the lyrics.
Jim Morrison wrote the second verse, and what was originally resembled a folk song quickly developed as Ray Manzarek came up with the iconic organ intro, and John Densmore came up with the rhythm.