Slime (スライム Suraimu) is a series of cards, mostly DARK/WATER Aqua/Fiend monsters, first used by Strings in Yu-Gi-Oh! and then by Mad Dog in Yu-Gi-Oh! GX and Declan Akaba in Yu-Gi-Oh! ARC-V. While it is a series in the OCG/TCG, it functions as an archetype in the Yu-Gi-Oh! GX anime.