Evil Shadow (魔影; maei) is a family premiered in BS02, and are themed after demons and evil knights. All Evil Shadow cards own the Purple color, until SD42 in which Kamen Rider Ghost Ore Damashii broke the trend.
Throughout the game history, the Evil Shadow family has gained a lot of different archetypes and supports. The first notable one was the Dark Knights, themed around the Arthurian legend, with The KnightHero Swordius-Arthur (though not within the archetype itself) being the leading card. The second main wave of support started in BS27, named the Fallen Knights, having the theme of the lost paradise. All the Fallen Knights play around the keyword Poison Blade. The third major wave of support was in BS50, pairing with the Youkai family to support The Grandwalker Tsukuyomi in a rush-based deck. Evil Shadow cards in this particular deck have an aesthetic theme of past Japanese warriors summoned from the dead. Last but not least, during Rebirth era, the Dragon Knights were introduced, again using the theme of Arthurian legend, but also elements from Les Misérables.
On the other hand, the Evil Shadow family is often seen to be owned by the Doll archetype, which focuses on the family Ogre Wizard and The Grandwalker Hera, though Evil Shadow existing in these cards do not affect the play style. The family is also seen in some cards that act as support for the God-Sechs cards, first seen with The Wandering Armor, and most noticeable in SD57.
On the collaboration side, Kamen Rider Ghost has taken the Evil Shadow family as part of its identity, since its nature is about past great spirits and "death", and got a lot of effects that specify both the Kamen family and the Evil Shadow family.