The Simpson universe has a cast of memorable, funny, and unique characters. Each episode centered on the dysfunctional Simpson family and their relationship with the other residents of Springfield like Moe, Mr. Burns, and Ned Flanders as well as guest stars, as they participated in a wide range of activities from athletic competitions to inhibiting the protagonists of scary stories.

Fans of the Simpsons might have come across a few episodes that weren't all pranks and funny unexpected situations, but brought tears to their eyes. Whether they were tears of joy or sadness, a box of tissues should be nearby when watching these episodes.

'Bart Sells His Soul' (Season 7, Episode 4)

Bart and Santa's Little Helper in 'The Simpsons'
Image via Walt Disney Company

Bart is one of the mischievous characters on the show. He's always pulling pranks on the residents of Springfield. There aren't many items that scare Bart. However, he did fear that he truly lost his soul after a bad transaction.

In season 7, episode 4, Bart sold his soul to Millhouse. This backfired for him when he started to experience strange events and activities around him. When Bart realized that Millhouse no longer has his soul, he's heartbroken. After praying for his soul, his sister told him that she bought it and returned it to him.

'I Love Lisa' (Season 4, Episode 15)

Valentine's Day card in 'The Simpsons'
Image via Fox Television Animation

Typically, during the holidays, children in school would bring in treats and cards to share with the rest of the class. The fairest approach to this tradition would be for everyone in the class to receive a treat that way no one feels left out when they don't receive a card.

In season 4, episode 15, one classmate, Ralph, didn't receive any Valentine's Day cards on Valentine's Day. Ralph cried after realizing that only he didn't get any cards. To cheer him up, Lisa gave him a card. However, Ralph thought that Lisa had a crush on him.

'Simpsons Roasting On an Open Fire' (Season 1, Episode 1)

Bart, Lisa, Maggie and Santa's Little Helper in 'The Simpsons'
Image via Fox Television Animation

Viewers were aware of The Simpsons after The Tracy Ullman Show introduced the spin-off series, and the first episode of The Simpsons didn't elaborate too much on reintroducing the characters again. The episode 'Simpsons Roasting On an Open Fire' premiered in December and showed the Simpson preparing for the holidays.

During this episode, Bart and Homer attend a greyhound racing event where they placed money on Santa's Little Helper. After the dog finished last and the owner furiously yelled at him. As Santa's Little Helper ran away from his owner, he jumps into Homer's arms. The adorable puppy eyes convinced Homer to adopt him.

'Lisa's First Word' (Season 4, Episode 10)

Bart Simpson walking away from Lisa Simpson in 'The Simpsons'
Image via Fox Television Animation

The Simpsons also showed some heart-filled moments, where they relived a positive memory, such as remembering the birth of their child. A lot of parents eagerly anticipate hearing the first word their child says whether it's "Mamma," "Dadda," or some other word.

This moment was no different for the Simpsons. As Homer and Marge along with the kids wondered when Maggie will tell her first word, they recalled the day Lisa was born. This Simpson episode also highlighted the sibling relationship between Bart and Lisa as Lisa began to receive more attention from her parents than Bart.

'Lisa's Wedding' (Season 6, Episode 19)

Lisa and Homer Simpson in 'The Simpsons'
Image via Fox Television Animation

Lisa and Homer may have different outlooks on life. Lisa engaged in highly intellectual conversations (for someone her age), while Homer was more concerned with eating donuts while drinking a glass of beer at the end of the day. Despite their differences, they still shared a strong father-daughter bond.

In season 6, episode 19, a fortune-teller predicted Lisa's future, specifically who the love of her life will be. The episode flashes forward to 2010 when Lisa and her fiancé were preparing for their wedding day. The real tearjerker moment began when Homer told her how proud he was of her and said "I always felt you were the best thing my name ever got attached to."

'Home Sweet Homediddly-Dum-Doodily' (Season 7, Episode 3)

The Simpsons Family with Ned Flanders and his wife in 'The Simpsons'
Image via Fox Television Animation

After six seasons of The Simpsons, viewers grew to know that the Simpson family had a unique relationship with each other. They would often get under each other's skins, especially when Bart was pulling pranks on Homer, but at the end of the day, they would forgive each other.

When Homer and Marge lost custody of the children, it was undoubtedly a sad day for the family. During this time, the children were taken care of by their next-door neighbors, the Flanders. Homer and Marge agreed to do anything to reunite their family again, including taking a parenting class.

'Alone Again, Natura-Diddily' (Season 11, Episode 14)

Marge Simpson and Maude Flander in 'The Simpsons'
Image via Fox Television Animation

Before Ned Flanders remarried Edna Krabappel, he was happily married to Maude Flanders. She arguably was Ned Flanders' soulmate, and both shared their devotion to the Christian faith. There were moments when Ned and Maude made mistakes, but they soon forgave each other in the end.

Season 11, Episode 14 served as the last episode where viewers got to see Maude alive. Maude's death was unexpected as she died right after being hit by a T-shirt from a shirt cannon. In that same episode, her funeral was held. Ned and her children grieved her death.

'Dog of Death' (Season 3, Episode 19)

Homer Simpson and Santa's Little Helper in 'The Simpsons'
Image via Fox Television Animation

Anyone who's witnessed first-hand losing a dog knows that it can take a toll on their days (until the dog is found and returned home). A dog is a member of the family, and if they are injured or lost, hurts other family members. In season 3, episode 19, 'Dog of Death,' the Simpson family dog, Santa's Little Helper, fell ill and required an expensive operation to relieve the knot in its stomach.

For the Simpson family, this required them to readjust their spending and budget for the operation. When they finally raised enough money for the operation and the operation proved to be successful, they are still left disappointed at how they had to give up their spending to afford the operation. If this wasn't enough, Santa's Helper runs away from the family.

'Mother Simpson' (Season 7, Episode 8)

Glenn Close as Mona Simpson kissing little Homer Simpson in 'The Simpsons'
Image via Fox Television Animation

The Simpsons also bear its family secrets. Throughout the 33 seasons (and counting), viewers learned more about the Simpson family and the residents of Springfield. For the longest time, there wasn't a lot of information about Homer's mother, Mona. Usually, only Grandpa Simpson, Patty, and Selma (Marge's sisters) would make their on-screen appearances on the show.

For the longest time, Homer believed that his mother passed away when he was very young. It wasn't until season 7, episode 8, "Mother Simpson," that Homer's mother finally appears. During the episode, Homer fakes his death to avoid a taxing responsibility. After towns folks told Homer that he saw Mona Simpson (voiced by Glenn Close), Homer's mother, alive, he visited her grave. It was at that moment that he was reunited with his mother. The reunion doesn't last too long as Mona had to return to hiding. The episode included flashbacks to Homer's childhood and gave insight into the relationship he had with his mother.

'Four Regrettings and a Funeral,' (Season 25, Episode 3)

Marcia Wallace voicing Edna Krabappel in 'The Simpsons'
Image via Fox Television Animation

Many actors have joined and left The Simpsons. The actors' characters that they voiced also left with them, either by slowly having fewer appearances on the show or by "killing them off." Actors who leave shows usually were because they decided to follow other projects, or were engaged in a dispute with the current cast and decided it was best to leave the show.

Sadly, some characters on the show died because the actor that voiced them died. Season 25, Episode 3 served as a tribute for Ms. Edna Krabappel as the voice actor, Marcia Wallace, passed away in October 2013. Ms. Krabappel taught fourth grade at Springfield Elementary School. Many characters saw her as an uncaring teacher, but when she retired from the show, it left a hole in some characters' hearts, and in the title sequence, Bart wrote "We'll really miss you, Mrs. K," on the chalkboard.

NEXT: The 9 Saddest Episodes From Otherwise Hilarious TV Sitcoms