Transcriptional deregulation is one of the core tenets of cancer biology and is underpinned by alterations in both protein-coding genes and noncoding regulatory elements. Large regulatory elements, so-called super-enhancers (SEs), are central to the maintenance of cancer cell identity and promote oncogenic transcription to which cancer cells become highly addicted. Such dependence on SE-driven transcription for proliferation and survival offers an Achilles heel for the therapeutic targeting of cancer cells. Indeed, inhibition of the cellular machinery required for the assembly and maintenance of SEs dampens oncogenic transcription and inhibits tumor growth. In this article, we review the organization, function, and regulation of oncogenic SEs and their contribution to the cancer cell state.