The degradation of RNA is a critical aspect of gene regulation. Correspondingly, ribonucleases exist within the cell to degrade RNA in specific cellular contexts. An important and conserved ribonuclease is called XRN1. This enzyme, an exoribonuclease, degrades RNA in a processive 5' to 3' direction. Substrates for XRN1 include decapped mRNA, endonucleolytically cleaved mRNA, lncRNA, and some aberrant tRNAs. In addition, XRN1 serves a vital role in the processing and maturation of the 5' ends of rRNA and snoRNAs. In this review, we discuss some of the important roles of XRN1 in the cell.