While in the employ of David Xanatos, Phobos transformed the runaway girl LaVonne into a vampire. He also developed the Medusa Device, which could turn organic matter to stone. Phobos, a paranoid man, intended to betray Xanatos, and to this end he secretly engineered the hybrid gargoyle Venus to be his personal bodyguard. However, Venus rebelled against his control of her, and Phobos was eventually killed when Demona stole the Medusa Device and used it to turn him to stone.
Phobos' role in the Marvel Comics series seems to mirror that of Anton Sevarius in the television series. In particular, turning a human into a winged creature (in this case a vampire) resembles the story of the mutates, and the character of Venus bears similarities to the clone Delilah.