The Jelly Overlord is a Legendary pet in Bubble Gum Simulator. It can be obtained by opening a Jelly Egg. The chance of hatching it is 1 in 100,000 (0.001%), or 1 in 50,000 (0.002%) with the Lucky Chancesgamepass.
It can also be obtained by blowing 15,000,000,000 bubbles and claiming the prize.