The Herwig 7.0 / Herwig++ 3.0 release marks the end of separate development for Herwig++ and HERWIG, becoming the first major release of the Herwig event generator family. This version includes significant improvements in event simulation, such as built-in next-to-leading order (NLO) calculations for Standard Model processes, matching to angular-ordered and dipole shower modules, and consistent treatment of perturbative uncertainties. The new version also features QED radiation and spin correlations in the angular ordered shower, and improved integration and unweighting with parallelization. The release includes a new online documentation system, updated manual, and support for external amplitude providers like GoSam, MadGraph, and VBFNLO. Electroweak corrections to VV production are implemented, and the angular-ordered parton shower is now as accurate as HERWIG 6. The shower includes QED radiation, spin correlations, and improved handling of gluon-to-quark-antiquark branching. The release also includes improvements to perturbative and shower uncertainties, with variations in renormalization and factorization scales for assessing uncertainties. A new tune for e+e- data has been developed, and the multi-parton interaction model has been tuned to match double parton scattering data. The release introduces new run modes and simplified input files for easier steering, and supports FxFx merging and Higgs boson pair production. Sample results show improved agreement with data for various processes, including thrust distribution, photon-jet energy fraction, and jet activity in t\bar{t} events. The release includes a comprehensive set of improvements, including a powerful framework for NLO calculations and enhanced shower modules. The release also provides a new documentation system and will serve as the basis for future developments such as multijet merging and electroweak corrections. The release is supported by various institutions and is available under the GNU General Public License.The Herwig 7.0 / Herwig++ 3.0 release marks the end of separate development for Herwig++ and HERWIG, becoming the first major release of the Herwig event generator family. This version includes significant improvements in event simulation, such as built-in next-to-leading order (NLO) calculations for Standard Model processes, matching to angular-ordered and dipole shower modules, and consistent treatment of perturbative uncertainties. The new version also features QED radiation and spin correlations in the angular ordered shower, and improved integration and unweighting with parallelization. The release includes a new online documentation system, updated manual, and support for external amplitude providers like GoSam, MadGraph, and VBFNLO. Electroweak corrections to VV production are implemented, and the angular-ordered parton shower is now as accurate as HERWIG 6. The shower includes QED radiation, spin correlations, and improved handling of gluon-to-quark-antiquark branching. The release also includes improvements to perturbative and shower uncertainties, with variations in renormalization and factorization scales for assessing uncertainties. A new tune for e+e- data has been developed, and the multi-parton interaction model has been tuned to match double parton scattering data. The release introduces new run modes and simplified input files for easier steering, and supports FxFx merging and Higgs boson pair production. Sample results show improved agreement with data for various processes, including thrust distribution, photon-jet energy fraction, and jet activity in t\bar{t} events. The release includes a comprehensive set of improvements, including a powerful framework for NLO calculations and enhanced shower modules. The release also provides a new documentation system and will serve as the basis for future developments such as multijet merging and electroweak corrections. The release is supported by various institutions and is available under the GNU General Public License.