For the first several years, the most recognizable DC characters were not released. DC Direct focused on lesser-known characters and comic series designed for mature readers such as The Sandman, Preacher, and Transmetropolitan. Later, DC Direct increased its production of recognizable characters such as Batman, Superman, Wonder Woman, The Flash, Supergirl, Batgirl, Starfire, Aquaman and Robin. Figures were first grouped randomly, then thematically and now in official "lines" that may be released over several years. The first three series in 1999 had variants for each figure, through the practice was quickly discontinued. DC Collectibles shares the licenses for many DC characters with other toy manufacturers, such as Mattel (which has the master toy license for all DC Comics properties), but Vertigo figures are released only by DC Collectibles.