The Perfect Ones

The Perfect Ones are the secondary antagonists in the short story "The Perfect School", the seventh story of Even More Tales to Give You Goosebumps, as well as its TV adaptation.

Personality
The Perfect Ones are designed to be a well behaved perfect version of the child they're replacing, devoid of all the flaws their human counterparts had.

Physical Appearance
The Perfect Ones look exactly like the child they're replacing. In the book, they're robots, while in the television adaptation, they are clones.

Trivia

 * The Perfect Ones are similar to class of 1947 as both of them have supernatural, tragic backstories that's caused by one red herring like Mr. Chameleon or The Guardians.