Bacillus Calmette-Guerin (BCG) is the common name given to a family of vaccines against human tuberculosis. Created in 1921 by the in vitro attenuation of a virulent Mycobacterium bovis in France, the BCG vaccine continues to generate debate and confusion after nearly a century of use. Since the 1940s, significant sequence differences among the BCG strains have been reported. In addition, relationships between the recombinant BCG vaccines used in current clinical trials and their parental strains have been never fully delineated. In order to standardize and to clarify the subject regarding common BCG strains used to generate those novel vaccines, a sequential emergence of the parental strains and their matching recombinant strains was built. Hence, for a total of 16 BCG strains in worldwide circulation, 9 have been used to sustain one or more genetic alterations, resulting in around 21 novel recombinant BCG strains. Although it is an outstanding achievement, only 2 out of the 21 recombinant strains are from the most immunogenic group. Systematizing the novel BCG vaccines and their parental strains may facilitate our understanding of protection provided by BCG immunizations.