The discovery of N-heterocyclic carbenes (NHCs) revolutionized organometallic chemistry due to their strong metal-ligand bonds. These strong bonds also lend enhanced stability to gold surfaces and nanoparticles. This stability and high degree of synthetic tunability has allowed NHCs to supplant thiols as the ligand of choice when functionalizing gold surfaces. This review article summarizes the basic science and applications of NHCs on gold surfaces and gold nanoparticles. Additionally, scientific questions that are unique to gold-NHC systems are discussed, such as the NHC adatom binding motif and the NHC surface mobility. Finally, new applications for NHCs on gold are covered with particular attention to biomedicine, catalysis, and microelectronics.