This book focuses on histone mutations, especially those mutations closely related to cancer. Genetic mutations and epigenetic alterations contribute to the development of a variety of cancers: recent genetic studies have identified e.g. H3K27M and H3G34R/V mutation in over 75% of DIPG cases, H3.3K36M mutation in more than 90% of chondroblastoma cases, and H3G34W/L mutation in over 90% of giant cell tumors of bone. Given the high incidence and tumorigenesis effects of histone H3 mutations, they are also referred to as oncohistones. This book highlights the advances made in the area over the past 10 years, and offers a state-of-the-art summary of epigenetic alternation, gene expression, protein structure, drug discovery, immunotherapy, and mouse modeling of histone H3 mutations in various tumors. Chiefly intended to provide researchers and graduate students with an overall picture of these mutations, it will also be of interest to researchers in basic oncology, clinical oncology, and epigenetics, as well as academics and clinical oncology practitioners.