1st Infantry is the debut solo studio album by American hip-hop producer and rapper the Alchemist.

It features guest appearances from the Lox, Mobb Deep, Big Noyd, Big Twins, B-Real, Chinky, Devin the Dude, Dilated Peoples, Illa Ghee, Lloyd Banks, M.O.P., Nas, Nina Sky, PSC, Stat Quo and the Game.

It also reached number 43 on the UK Independent Albums chart.

The album's instrumental version and deluxe edition with a bonus DVD were released on October 4, 2005.

The song "Bangers" appeared in the 2006 video game Saints Row.