Gerald Samson

Baby Gerald, also known as the baby with one eyebrow, is Maggie’s arch-nemesis. He made his first appearance in “Sweet Seymour Skinner's Baadasssss Song.” He is voiced by Hank Azaria. In that episode, Lisa referred to Baby Gerald as Maggie’s rival. Gerald is distinguished by his unibrow, being one of the few characters in the show to have one.

On a few occasions, Gerald has been shown being pushed in a stroller by his mother outside the Simpsons’ house, with the two babies glaring at each other, the camera focusing on their narrowed stares. Homer often mistakes Maggie for Baby Gerald.

Gerald apparently has a history of causing large scale public incidents and was once rescued from an unspecified disaster by Bart’s mail order “wonder dog” Laddie. Both dog and baby were participants in a ceremony presided over by Mayor Quimby, during which the mayor inquired, "Baby Gerald, we can't help but wonder what mischief you'll get into next."

Future
In Bart to the Future, it is revealed that Maggie and Gerald stopped being enemies, got married, and even had a baby together. The baby was named Margareth "Maggie" Jr. after her mother.

Simpsons HD
In the new Simpsons sequence, when Marge goes to the supermarket, it shows Maggie shaking her fist at Gerald.

Appearances

 * Sweet Seymour Skinner's Baadasssss Song - Gerald is seen being pushed in his stroller outside the Simpson's home. Maggie and Gerald exchange sinister glares. Lisa refers to Gerald as Maggie's nemesis
 * Lady Bouvier's Lover - Maggie and Gerald once again exchange sinister glares.
 * The Canine Mutiny - Gerald is rescued by Bart's mail-order dog, Laddie. In this scene, he referred to as a troublemaker.
 * The Joy of Sect
 * Last Tap Dance in Springfield
 * Marge vs. Singles, Seniors, Childless Couples, Teens and Gays - Maggie and Gerald are seen being involved in the baby riot known as the Tot Offensive. During this riot, Maggie is seen beating up Gerald.
 * The new Simpsons intro - More fist shaking.