The Tombusvirus group, first established in 1971, comprises a diverse assemblage of small, positive-sense single-stranded RNA viruses belonging to the family Tombusviridae (order Tolivirales, class Tolucaviricetes). The family currently encompasses three subfamilies (Procedovirinae, Regressovirinae, and Calvusvirinae), 18 genera, 1 unassigned genus, and approximately 93 recognized species. Named after Tomato bushy stunt virus (TBSV)—the first icosahedral virus to be crystallized—members of this family have served as fundamental models for elucidating the structural and molecular mechanisms of RNA virus biology. The virions are non-enveloped, icosahedral particles (T = 3; 30–35 nm in diameter) encapsidating monopartite genomes of ~4.5–4.9 kb, except for the bipartite Dianthovirus. Their genomes lack both a 5′ cap and a 3′ poly(A) tail but employ 3′ cap-independent translation enhancers (CITEs) that mediate long-distance RNA–RNA interactions with the 5′ UTR to recruit host translation factors such as eIF4F. Typically, four to seven open reading frames (ORFs) are encoded, with ORF1 producing the replication protein, and the RNA-dependent RNA polymerase (RdRp) generated via translational readthrough (ORF1-RT) or −1 ribosomal frameshifting. Replication involves key proteins (p33, p92) forming membrane-associated complexes. Phylogenetic analyses of conserved RdRp domains reveal extensive genetic divergence among subfamilies. Additionally, the discovery of tombusvirus-like sequences in fungi and invertebrates expands the ecological and evolutionary scope of this viral family. Overall, Tombusviridae represents a pivotal model system for understanding RNA virus replication, translation, and evolutionary dynamics.