Big Baby

Big Baby is one of the supporting antagonists in Toy Story 3, but in the end he reformed.

Backstory
Big Baby, along with Lotso and Chuckles, was once owned by a young girl named Daisy, living at her house, as was revealed to Woody by Chuckles himself. Among them all, Lotso was the most special to her. One day, during a break at a rest stop, Daisy was playing with her toys when she stopped to have some lunch, after which she fell asleep and forgot them there. The three waited day in and day out for Daisy to return to them, but on one rainy day, they decided to make the journey back to her house when she didn't come back for them; however, upon arriving, Lotso glimpsed through the window at Daisy playing with an identical bear. Angered that she had replaced him, he then convinced Big Baby that they all had been replaced and that Daisy no longer loved him, as well as intimidated Chuckles into remaining silent as to the truth.

The three toys then hitched a ride on the back of a truck before being thrown off by a bump in the road and landing in front of Sunnyside Daycare, which Lotso proceeded to take over using Big Baby as his enforcer, due to his considerable size in comparison to the other toys.

Toy Story 3
Big Baby, along with Lotso and Chuckles, once used to be owned by a girl named Daisy, who had once loved them all. One day when Daisy went out on a drive with her toys and parents for a picnic, she fell asleep and was carried back to the car without Lotso, Chuckles, or Big Baby, leaving them stranded at the countryside. The three toys eventually made it back to Daisy's house, only for Lotso to discover that Daisy got another Lots-o'-Huggin' Bear toy. This made Lotso snap and turn evil, and he made Big Baby and Chuckles follow him. Big Baby wanted to take a peek at Daisy, but Lotso pulled him down from the window, snatched Big Baby's pendant off from his clothes, threw it on the ground, and pulled him away from Daisy's house. They hitched a ride on the back of a Pizza Planet delivery truck until they arrived at Sunnyside, where they rose to power, with Big Baby becoming Lotso's chief enforcer (his eye was also broken when he fell off the Pizza Planet truck).

On the first night, when Andy's toys are imprisoned in the Caterpillar Room, Big Baby separates Mr. Potato Head from the other toys by imprisoning him in a sandbox. The next night, Big Baby stands as a guard while Ken and a reset Buzz (who now serves as one of Lotso's helpers) take roll call to make sure that all the toys are there, then the three walk off to capture Mr. Potato Head after discovering a real potato inside his cell. Once again, Big Baby imprisons Mr. Potato Head in the sandbox outside after Mr. Potato Head kicks Ken in the shin, though this is revealed to all be part of the toys' escape plan.

During the escape, while Big Baby is rocking slowly on a swing and looking up at the night sky, Woody, Buzz (who has now been set to his Spanish mode by the toys by accident), and the other toys sneak past Big Baby as they make their way to the trash chute (the only escape route that the Chatter Telephone has pinpointed to Woody), but they accidentally get Big Baby's attention when one of the Aliens trip, making him land with a squeak. Big Baby gets off the swing and walks over to the source of the sound, but the toys dive under a plastic sand bucket at the last moment, so that Big Baby finds nothing when he reaches the spot where the toys have been standing.

In the trash chute, after Big Baby, Lotso, and the other Sunnyside toys surround Andy's toys at an open garbage dumpster, Woody brings up the subject of Daisy and shows Lotso and Big Baby an object he has received from Chuckles during his stay at Bonnie's house: Big Baby's old pendant. Upon catching sight of his old pendant, Big Baby suddenly remembers Daisy. As Woody tries to tell the truth about Daisy to Lotso (who doesn't want anything to do with Daisy) and Big Baby, Woody tosses the pendant to Big Baby, who picks it up to take a look at the token of his lost love and shows that he still cares about her, whom he affectionately refers to as "Mama." Lotso suddenly insults Big Baby for loving Daisy again, yelling to him that she has never loved him as he snatches the pendant away from Big Baby, slams it onto the dumpster lid, and smashes it into pieces with his cane. Seeing his last remaining memento of his old owner being destroyed, Big Baby begins crying, and then Lotso pokes Big Baby abusively with his cane for thinking like a dummy, causing Big Baby to yowl in pain. Big Baby then sees what is going on and what Lotso has done to him: Lotso had taken him away from Daisy, and he realizes that Lotso is not his friend. Having had enough with all of Lotso's lies and bullying, Big Baby lifts up the vile and selfish bear from behind, throws him into the dumpster, and closes the dumpster's lid on Lotso, redeeming himself in the process. He then blows a raspberry at Lotso and helps Woody and his friends climb to safety.

During the credits, Big Baby is shown to be living a happier life at a now cool and groovy Sunnyside under the care of Ken and Barbie, the new leaders. When the Sunnyside toys have a "beach party" at the sandbox, Big Baby is seen next to Barbie as he makes a sand castle and pats it with a shovel, but the castle collapses. This makes Big Baby cry, but he is immediately consoled by Barbie, who hands his bottle of milk to him, and he puts the bottle's tip into his mouth and coos as Barbie caresses him. That night, when a disco is held in the Butterfly Room, Big Baby is seen wearing a diaper that sparkles, similar to a tuxedo and trousers that Ken is wearing and a dress that Barbie is wearing. He joins Ken and Barbie and hugs the two in his arms as he happily spins the couple around in a spotlight.

Toy Description
From Official Website:

"Your little one will love this baby doll with his soft, cuddly fabric body and vinyl arms, legs, and face. With dazzling blue eyes that open and close, this realistic baby encourages nurturing play. Eighteen inches tall, he comes dressed in an adorable yellow onesie with matching bonnet, and has his own magical bottle of milk that disappears while he drinks! A perfect first doll for your special child. Machine washable on gentle cycle. Flame retardant."

Trivia

 * The way in which Big Baby throws Lotso into the dumpster mimics a scene in Star Wars Episode VI: Return of the Jedi, in which Darth Vader/Anakin Skywalker, throws Emperor Palpatine into the reactor shaft of the Second Death Star to save his son Luke Skywalker. Although this may only be a possible reference, unlike the ones from the previous Toy Story films.
 * Big Baby has what appears to be a lazy-eye, which was caused when he was knocked of the truck and landed near Sunnyside. It is also a possible reference to Babyface.
 * Before Daisy accidentally left her toys, Big Baby wore a yellow onesie with a matching bonnet. However, when he and Lotso got to Sunnyside, Big Baby wasn't wearing the outfit anymore. It is unknown what happened to the onesie; he lost his bonnet when he fell off the truck and also broke his left eye.
 * Big Baby's tattoo's may have been based off concept art of Ducky, which depicts tattoos drawn on by Sid.
 * Big Baby is based on a baby doll that Lee Unkrich's daughter, Hannah had when she was growing up.
 * In Sweden, he is named Babyface, just like one of Sid's toys.
 * Big Baby does have a physical appearance in Toy Story 3: The Video Game, but only a silent cameo on the Sunnyside level for the PS3.
 * It is likely that he is adopted by Ken and Barbie afterwards. This can be seen when Barbie coaxes him when he is crying after his sandcastle collapses.