Starting the final phase of the Beast Era, when in 1999-2000 the Beast Wars series ended and was replaced with Beast Machines. In the narrative, only the heroic Maximals kept their animalistic roots, though they tended to turn into mechanical beasts rather than organic ones. They fought against Vehicons, villains that turned into vehicles.
First up, here is Blackarachnia, who has switched allegiances and is now a Maximal. She turns into a techno-organic spider.