Blackarachnia is a Transformer character from Beast Wars. During the Beast Wars series, she was originally a Maximal ProtoForm, but her stasis pod was stolen by the Predacons and reprogrammed by Tarantulus as an Predacon spy and saboteur. Her beast form is a black widow spider.

One of the first female Transformers to become a major character, Blackarachnia is beloved by fans for her ingenuity, take-charge attitude, and her ability to look after herself — something that previous female characters had been lacking. Originally, this character was intended to be a quick retool of an earlier design, but animators ended up giving Blackarachnia a very feminine design, supposedly inspired by exotic dancers.

Eventually, Blackarachnia began a relationship with the Maximal Silverbolt , who continually tried to bring her over to the side of good. In the end, Silverbolt's efforts prevailed; Blackarachnia rejected her Predacon ways and became a Transmetal-2 Maximal fighter.

Blackarachnia was one of eight characters to survive Beast Wars and go on to the Beast Machines series. At this point, she underwent a sort of "role-reversal," and she spent a great deal of time looking for her love Silverbolt and freeing him from the Vehicon he became.

She was voiced by Venus Terzo (English) and Ryoka Yuzuki (Japanese).