Javier "Javi" Grillo-Marxuach (listenⓘ; born October 28, 1969, in San Juan, Puerto Rico), is a television screenwriter and producer, and podcaster, known for his work as writer and producer on the first two seasons of the ABC television series Lost, as well as other series including Charmed and Law & Order: Special Victims Unit.

The writing staff won the Writers Guild of America (WGA) Award for Best Dramatic Series at the February 2006 ceremony for their work on the first and second seasons.

[6] The writing staff were nominated for the WGA Award for Best Dramatic Series again at the February 2007 ceremony for their work on the second and third seasons.

[10] He is also writer of Dynamite Entertainment's four-issue limited series Classic Battlestar Galactica: Cylon Apocalypse.

Alongside Jose Molina, he is also the co-host of the Children of Tendu Podcast, a weekly series offering advice for getting into the television industry.