Meltryllis

Also known as: Mysterious Alter Ego Λ (Nazo no Alter Ego Λ; 謎のアルターエゴ・Λ), Mysterious Alter Ego Lambda, Lambdalilith, Lambdaryllis, Meltlilith (Lancer), Meltryllis (Lancer), Leviathan, Cruel Swim Tutu

Meltryllis (also romanized as Meltlilith) is an Alter Ego-class High-Servant of BB in the CCC Incidents of Fate/Extra CCC and Fate/Extra CCC Fox Tail. She is one of the Servants of the Protagonist of the Grand Order conflicts of Fate/Grand Order.

(Source: TYPE-MOON Wiki)