In plants Heat Shock Factors (HSFs) are encoded by large gene families and are primary regulators of responses not only to high temperatures but also to a number of other abiotic stresses and pathogen threats. Here we provide an overview of the diverse world of the plant HSFs through analysis of their functional versatility, regulation and interactions. HSFs can regulate tolerance to a number of extreme conditions including high or low temperatures, drought, hypoxic conditions, soil salinity, toxic minerals, strong irradiation or pathogen defenses. Variability is reflected in expression control with considerable differences in transcript profiles of individual HSF genes. Moreover, alternative splicing and posttranslational modifications provides further variability. HSFs are involved in complex web of protein-protein interactions which include formation of homomeric and heteromeric HSF trimers, and complexes with a number of other regulatory proteins including transcription regulators, chromatin-associated proteins or heat shock proteins (HSPs). Interactions of the Arabidopsis HSFA4A with proteins which control transcription, cellular homeostasis, responses to different stresses and programmed cell death, illustrate the complexity of the regulatory networks related to a plant HSF. Diversity in plant HSFs facilitates the adaptation to multiple adverse environmental conditions, an important feature in response to climate change.