Windseeker, Knott’s Berry Farm, California, USA

The circular swing ride stalled, leaving 20 people stranded 300 feet (91m) in the air for nearly four hours. No one was injured, but the evacuation, which took three hours and forty minutes, is one of the longest on record for any amusement ride. Two weeks earlier the same ride stalled and left 15 people stranded for about three hours and in July, Windseeker at Carowinds near Charlotte, North Carolina stalled and left 25 riders stranded hundreds of feet in the air for nearly three hours. In June, the same ride at Cedar Point in Sandusky, Ohio left 29 riders stranded 150 feet (46m) in the air for more than an hour when it stalled. All six of the Windseeker rides operating at parks throughout the Cedar Fair chain were ordered closed for the rest of the season. Source

Mega Bounce Frog, Travelling Fair, Leicester, UK

A ride car came loose, throwing out a 16 year old passenger, and leaving the other hanging precariously. The boy remaining in the car was injured by safety barriers as the ride continued to turn. He was treated in intensive care for extensive injuries including a collapsed lung. The boy who was thrown from the ride suffered injuries including a broken nose.  Source

Trafikplasten, Furuviksparken, Gävleborg, Sweden

A 31-year-old man was hospitalized with blood poisoning and internal injuries after he boarded the kiddie car ride in an attempt to assist his daughter and his rectum became impaled on a tow hitch that protruded from behind the vehicle. Source (in Swedish)

Trafikplasten Furuviksparken Accident
Ride vehicle with tow hitch (which have since been removed).

Kingda Ka, Six Flags Great Adventure, New Jersey, USA

A man suffered neck and face injuries when a bird flew into his face while on the coaster. Source

Vampire, Six Flags La Ronde, Québec, Canada

A maintenance worker was struck by the coaster’s moving train and killed instantly after he entered a restricted area. Source