Bacteriophages are the most numerous biological entities in the biosphere, and although their genetic diversity is high, it remains ill defined. Mycobacteriophages-the viruses of mycobacterial hosts-provide insights into this diversity as well as tools for manipulating Mycobacterium tuberculosis. We report here the complete genome sequences of 138 new mycobacteriophages, which-together with the 83 mycobacteriophages previously reported-represent the largest collection of phages known to infect a single common host, Mycobacterium smegmatis mc(2) 155.