eggette
A Sonic original fan character based off of Dr. Eggman as he appears in Sonic Mania. Also sometimes called Omelette or Eggatha.
In Flying Battery Zone Act 2, Eggman fights the player in a spider mecha internally referred to as the "Spider Mobile". The original sprite she derived from simply had Eggman hanging upside down in the mecha. The trend only really began to take off due to an interpretation by Alpha Gamboa; due to the fact that his visible face looked like that of a young girl in that state, the user had drawn the "head" of that sprite as a young girl with Eggman's trademarked glasses and a tiara reinterpreted from Eggman's nose, and her costume directly inspired from the Spider Mobile's design. From that point on, fans began to draw the character closely resembling that original version.
In most versions she's portrayed as an entity akin to Bowser Jr.: a bratty younger version of her "parent". However, whether she's actually related to Eggman or not is usually up for interpretation; in some she's blood by cloning, by her being a niece, or some coupling, and in others she's an android powered by a jewel on her head. In any case, she is just as technologically proficient as her originator and antagonizes Sonic the Hedgehog as well.
Do not mistake her for a younger genderswap of Dr. Eggman (see Eggma'am for a genderswap instead), nor a transformation in the vein of Super Crown fan characters (which often use the "-ette" suffix in English).