Gallery

Lucifer has adopted many appearances over the series to approach the hero and encourage him to think his options over carefully in the hope that, ultimately, the hero will side with Lucifer instead of the Great Will (or YHWH). You can have a look at them here.

Angel Lucifer: Also known as: Helel
Appearance: Shin Megami Tensei I, Shin Megami Tensei II, Persona 3/FES/P3P, Persona 4, Devil Summoner–Raidou Kuzunoha vs King Abaddon
Demon Lucifer: Also known as: Lucifer
Appearance: Shin Megami Tensei I, Shin Megami Tensei II, Shin Megami Tensei: Nocturne, Persona 3 FES/P3P, Persona 4, Devil Summoner–Raidou Kuzunoha vs King Abaddon
Blonde (sic) Man: Also know as: Louis Cypher
Appearance: Shin Megami Tensei I, Shin Megami Tensei II
Child and Nanny: Also known as: —
Appearance: Shin Megami Tensei: Nocturne (overworld)
Old Man and Maid: Also known as: —
Appearance: Shin Megami Tensei: Nocturne (Amala Labyrinth)
Young Blonde (sic) Man: Also known as: Louis Cyphre (sic)
Appearance: Devil Summoner–Raidou Kuzunoha vs King Abaddon
Strange Girl: Also known as: Louisa Ferre
Appearance: Shin Megami Tensei: Strange Journey

The pictures come from Be Your True Mind, where you can see the above even bigger, and many, many more Shin Megami Tensei pictures. The Louis Cyphre and Louisa Ferre pictures are from the Megaten wikia.