Oh boy I had a lot of fun thinking which ones would fit Penny but I only had so much space and time.

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Ultron from Marvel

Aigis from Persona 3

Miku Hatsune from Vocaloid

Monsoon from Metal Gear Rising (I feel so bad using this color palette with the context of that character)

Mettaon from Undertale

Genos from One Punch Man

Jenny Wakeman/XJ-9 from My Life as a Teenage Robot

Robo-Fortune from Skullgirls

Android 16 from Dragon Ball Z