Ice-E

Ice-E is the mascot of the "Monster Kidz Word Search" puzzle given to the player by sans. In it, he beckons to the reader "Hey kid's! Can you help me solve this puzzle?".

Strangely, there is an unnecessary apostrophe in "kid's". This, along with the fact that his puzzle is unsolvable, call into question his aptitude at puzzle making. Ice-E's word search, however, has been noted to contain oddly clairvoyant predictions about the future of the player's adventure.

Though Toby Fox called Ice-E the "greatest and most popular Undertale character" on his Twitter,

Ice-E never appears in game, leaving players to speculate at the limitless power he must possess.