United Airlines made headlines again recently after the company told a woman, who had already boarded, that she had to give up the seat she paid for her 2-year-old son to a standby passenger.

The incident follows a number of controversial passenger- and animal-related incidents for the airline this year.

Here are the ones you should know.

Shirley Yamauchi, June 2017

Shirley Yamauchi and her 2-year-old son, Taizo, boarded a plane in Houston on June 29 – the final leg of an 18-hour flight from Hawaii to Boston. Yamauchi said a flight attendant came to check if the child was present before a standby passenger showed up with a ticket corresponding to the toddler's seat number, Hawaii News Now reported.

Yamauchi said she alerted the problem to a flight attendant, who said that the flight was full and walked away.

Yamauchi continued the flight with her son on her lap, and said she was afraid of a physical confrontation if she spoke up further.

UNITED GIVES AWAY 2-YEAR-OLD'S SEAT TO STANDBY PASSENGER

"I started remembering all those incidents with United on the news. The violence. Teeth getting knocked out. I'm Asian. I'm scared and I felt uncomfortable. I didn't want those things to happen to me," she told Hawaii News Now.

United told Fox News that it has apologized to Yamauchi and her son, saying that it had "inaccurately scanned the boarding pass of Ms. Yamauchi's son. As a result, her son's seat appeared to be not checked in, and we released his seat to another customer and Ms. Yamauchi held her son for the flight."

Lucie Bahetoukilae, April 2017

Lucie Bahetoukilae had a ticket for an April 24 flight to Paris from New Jersey, but was placed on a plane that went to San Francisco, WABC reported.

Bahetoukilae only speaks French. She said the airline suddenly changed the gate for her trip and that it didn't announce the change in French or email her.

Bahetoukilae claimed the airline scanned her boarding pass and she went on the plane. Her niece, Diane Miantosko, told WABC that someone was in her aunt's seat, and that a crew member saw Bahetoukilae's pass and seated her elsewhere on the plane.

"We deeply apologize to Ms. Bahetoukilae for this unacceptable experience," United told Fox News. "When she arrived in San Francisco, we ensured she got on the next flight to Paris and refunded her ticket."

Simon the rabbit, April 2017

A large rabbit named Simon died following a flight from London to Chicago on April 20. The animal was supposed to fly an onward leg to Kansas City, Mo., after landing at Chicago’s O'Hare International Airport.

A lawyer for the group that purchased the three-foot-long rabbit announced possible legal action in May. The group claimed that the airline cremated the animal without permission after it was found dead, and that an airline employee locked the rabbit in a freezer for 16 hours, according to PEOPLE magazine. The group had planned to show the rabbit at the Iowa State Fair. United told the publication that "the assertion that Simon died in a freezer is false."

The airline said Simon was in "apparent good condition at 10:25 am" when he got to O'Hare. A kennel representative saw Simon "moving about within his crate about 11:00 am," it said. "Shortly thereafter, a kennel representative noticed Simon was motionless and that he passed away."

However, United reached "a satisfactory resolution" with the animal’s U.K. breeder, Annette Edwards, according to airline spokesman Charlie Hobart. He said that Edwards was United's customer and she had turned down an offer of a post-mortem examination.

Michael Hohl and Amber Maxwell, April 2017

Michael Hohl and Amber Maxwell boarded an April 15 flight from Houston to Costa Rica for their wedding. A man was asleep in the couple's seats in economy and they sat elsewhere on the flight, Hohl told KHOU. The new seats were in economy plus.

A flight attendant asked the couple if they were in the right seats - but the bride and groom admitted they weren't and inquired about an upgrade, the station reported. They were told to go back to their assigned seats.

The couple did so without incident, and a U.S. Marshall later asked them to get off the plane, according to Hohl. Hohl said he and his fiancee complied.

"These passengers repeatedly attempted to sit in upgraded seating which they did not purchase and they would not follow crew instructions to return to their assigned seats," United told the station, saying it rebooked the couple's flights.

Dr. David Dao, April 2017

Dr. David Dao was already seated when he was forcefully dragged from a fully-booked United Express flight on April 9 in Chicago. The ordeal started because he refused to give up his seat to make room for crew members.

Dao had a "significant concussion," lost two of his front teeth, and suffered a "serious broken nose," his attorney Thomas Demetrio said at a press conference.

Cellphone video of the disturbing incident prompted widespread outrage and created a public-relations nightmare for United. United CEO Oscar Munoz issued multiple statements, ultimately saying in his third statement that the incident was a "truly horrific event."

"No one should ever be mistreated this way," he said at the time.

In the wake of the incident, United now offers a $10,000 incentive to people who forfeit their seats.

"What happened to my dad should never happen to any human being," Dao's daughter, Crystal Dao Pepper, has said.

Dao eventually settled with the airline for an undisclosed amount in late April.

Jacob the golden retriever, January 2017

Kathleen Considine blamed the airline for the death of her dog Jacob, who traveled from Michigan to be with her in Oregon.

She wrote in a Facebook post that the golden retriever had a layover in Chicago, and that an airline worker in Detroit said the large dog would fit on both of his flights. She said the dog, however, didn't fit on his Portland flight, and he spent 20 hours in a kennel.

Considine claimed the dog was "disoriented and non-responsive" when he got to Portland. "After rushing Jacob to the emergency vet when his breathing became scarce, he was pronounced dead after 8 min of CPR," she wrote.

Jacob had been booked in a crate that was smaller than the one he arrived in, Hobart told Fox News. A Detroit agent "mistakenly told the customer that we'd be able to get that crate on the [final Portland-bound] flight," he said.

Hobart also said that Jacob had food, water and bathroom breaks while at the kennel, and that the airline refunded Considine's shipping costs.

Jacob "showed no signs of distress" nor did he "behave in a way that would suggest he was unwell while in our care,” the airline told WDIV.

The Associated Press contributed to this report.