A police dashcam video shows Richard Hubbard III, 25, being beaten during a traffic stop in the Cleveland suburb of Euclid, Ohio. Officer Michael Amiott can be seen repeatedly punching Mr. Hubbard, who is black, and hitting his head on the pavement.

Cellphone video shows Demetrius B. Hollins, 21, being kicked in the head and punched in the face by two officers during a traffic stop. The Gwinnett County Police Department later dismissed 89 cases involving the officers, Robert McDonald and Sgt. Michael F. Bongiovanni, who were fired and face criminal charges.

Footage from a dashboard camera and a cellphone shows Nania Cain being thrown to the ground and repeatedly punched in the face by an officer who claims Mr. Cain had allegedly jaywalked. Mr. Cain, 24, was initially charged with resisting arrest, but was released the next morning. The Sacramento police officer was placed on paid administrative leave.

Dejuan Hall, 23, was chased and apprehended by a police officer who is seen punching Mr. Hall and striking him with an object. In a bystander video, people can be heard yelling, “Police brutality.” The Vallejo police officer then shouts back: “Shut up. Get back,” and brandishes his gun.

Cellphone video shows a police officer slamming a 15-year-old female to the floor in effort to stop a fight involving three students. Officer Ruben De Los Santos was placed on paid administrative leave, and did not face criminal charges. He resigned in March.

Jacqueline Craig, 46, and her daughters, ages 15 and 19, were arrested after reporting to police that a neighbor had choked her 7-year-old son for littering. Bodycam video shows the responder, Officer William Martin, asking the mother, “Why don’t you teach your son not to litter?” Later, he aims a Taser toward the family and then handcuffs the women. Mr. Martin received a 10-day suspension for excessive force and continues to defend his actions.

Charles Kinsey, a behavioral therapist, was trying to help a young man who has autism when Mr. Kinsey was shot in the leg by a North Miami police officer. Jonathan Aledda, the officer, was fired for shooting the 47-year-old. His commander, Emile Hollant, is to be fired as well.

Carnell Snell Jr., 18, was fatally shot by the police in a strip mall parking lot. Surveillance video shows Mr. Snell running into the parking lot while tucking what appeared to be a handgun into his pants. The video was released after two days of protests over the shooting.

Keith Lamont Scott, 43, was fatally shot by the police at his apartment complex. The police were there to serve someone else with a warrant. Mr. Scott had parked his car in a visitor’s space, where he often waited for one of his children to return home on a bus. The video was captured by his wife on her cellphone.

Terence Crutcher, 40, was fatally shot by a Tulsa police officer who was responding to reports of an abandoned vehicle in the road. Footage from the dashboard camera of a police car shows Mr. Crutcher walking toward a car with his hands raised before being Tasered and then shot.

Videos taken from police officers’ body and dashboard cameras show two officers firing their guns at a stolen car moments before the driver, Paul O’Neal, 18, crashed it into a police vehicle. Mr. O’Neal was shot and killed in the back as he fled the scene and ran behind a nearby house. Police officers could be seen gathering around Mr. O’Neal as he lay on the ground.

Dashboard camera audio suggests that police officers tried to hit Joseph Mann with their patrol car as he fled on foot. “I’m going to hit him,” one officer is heard saying. “Go for it,” another says. Officers then followed Mr. Mann on foot and fired 18 shots, 14 of which hit him.

Philando Castile, 32, was fatally shot during a traffic stop in a St. Paul suburb, the aftermath of which was captured in a grisly video recorded by the car’s front-seat passenger and streamed live as the man slumped against her. Her young daughter sat in the back seat. In June, a jury found the Minnesota police officer, Jeronimo Yanez, not guilty of all charges, including second-degree manslaughter. Dashboard camera video was released days later.

A cellphone video shows a black man, Alton Sterling, 37, being tackled and then held to the ground by two white officers. Someone shouts, “He’s got a gun!” and one officer appears to hold a gun above Mr. Sterling’s chest. Multiple gunshots are heard while Mr. Sterling is pinned down. Mr. Sterling died at the scene.

Videos, apparently shot by students in a high school classroom, show a white school police officer grabbing an African-American student by the neck, flipping her backward as she sat at her desk, then dragging and throwing her across the floor.

James Blake, a retired tennis star who is biracial, was standing outside a Manhattan hotel when Officer James Frascatore threw him to the ground, mistaking him for a thief. Investigators studying the surveillance video concluded that the officer had used excessive force.

Surveillance cameras at a car dealership showed what occurred just before a white rookie police officer shot and killed Christian Taylor, 19, an unarmed black college student and football player. Officer Brad Miller was fired for using poor judgment.

The body camera for Officer Ray Tensing, of the University of Cincinnati police, captured the moment when he shot Samuel Dubose, 43, during a traffic stop involving a missing front license plate. Officer Tensing, who is white, faced a jury twice on charges relating to the death of Mr. Dubose. Both times ended in a mistrial.

Dashboard camera video revealed that the white Texas State trooper who pulled over Sandra Bland, 28, threatened her with a stun gun as their encounter escalated, partly because of her apparent unwillingness to snuff out a cigarette. Ms. Bland, a black woman, was arrested and later found dead in a jail cell.

Cellphone video showed a white police officer, David Eric Casebolt, pointing a gun at teenagers in bathing suits and shoving a black girl’s face into the ground.

Freddie Gray, 25, suffered a spinal injury while in police custody. He died a week later. The six officers involved in his arrest, a mix of black and white, were charged with crimes that included murder and manslaughter.

A bystander recorded a white officer, Michael T. Slager, shooting an unarmed black man, Walter L. Scott, 50, in the back as he ran away. The video showed Mr. Slager firing eight times then casually walking over to Mr. Scott, who was pronounced dead at the scene.

Surveillance video showed Officer Timothy Loehmann, who is white, hopping out of a police cruiser and immediately firing two shots at Tamir Rice, 12, killing him at close range. Before the shooting, Tamir, who was black, had been using a fake gun that looked strikingly like the real thing.

A dashcam video shows Laquan McDonald, 17, running, then walking past police officers when he is struck by bullets. One of the officers, Jason Van Dyke, who is white, was charged with murder on Nov. 24, 2015. Mr. McDonald, who is black, was shot 16 times.

A bystander’s video showed Michael Brown, 18, lying in the middle of the street after being shot and killed by a white officer named Darren Wilson. His body stayed in the street for hours. He was unarmed. Mr. Wilson was not indicted.

Eric Garner, 43, died after police officers tried to arrest him for the illegal sale of cigarettes. He was wrestled to the ground and placed in a chokehold. A cellphone camera held by a friend recorded the struggle as Mr. Garner told the police multiple times, “I can’t breathe.”