Take Me Out At the Ball Game

"Take me out at the ball game,

Take me out in the crowds;

Hit me with poison and a car jack,

I don't care if I'm stabbed in the back.

Let me die, die, die on the home plate,

If they don't weep, it's a shame.

For it's one, two, three hits, you're dead,

At the old ball game."

A person getting murdered at a sporting event. Creates a situation with hundreds of witnesses, but isn't necessarily easier for the detectives, as poison tends to be involved.

Title is a reference to the unofficial anthem of baseball. The quote is Silent Hunter's re-write of the lyrics of the chorus.

Anime and Manga

 * Three episodes of Detective Conan feature crimes that take place at sports events.
 * One occurs at a pro soccer game. A criminal calls the TV station covering the event and try to extort money out of them by claiming to have a gun. The criminal demands a large sum of cash, threatening to start shooting randomly into the crowd if it is not delivered in time. The police attempt to catch the criminal when they come the claim the money, but it turns out that the person had an accomplice who was observing the retrieval and are forced to let her go until they can find the accomplice. Conan eventually finds him and confronts him in a risky showdown with the criminal that nearly gets him killed. Of course, he is the titular character, so he lives.
 * The second case takes place at the high school baseball championships, an all-day event that covers the semi-finals and finals all at once. A mad bomber has decided to destroy the entire stadium and everyone in it, and it is up to Conan, Hattori, and police inspector Nakamura to find the cell phones the bomber has scattered throughout the stadium containing clues that eventually lead to him. In the end, the bomber's motive was some kind of convoluted revenge for his son's accidental death. Of course, it the fault actually rested largely with the son, who had overworked himself training and thus was unable to avoid getting run over on his way home, but the man still blamed the sport anyhow and planned to destroy the stadium as a form of symbolic revenge.
 * A third takes place at Wimbledon. A man blamed the defending champion for his mother's death because he had hoped to get enough money to pay for her operation by betting on the other competitors the previous year, and as a result could not afford the operation when the person he bet on lost. He planned to blow up the champion's mother at the end of the final match in revenge. Conan managed to identify him and took him out before he could activate the detonator.
 * One episode of Golgo 13 has the title character killing a star football player in the middle of a game.
 * One of the first chapters of City Hunter involves Ryo shooting a boxer during a match. Notable as it's one of the very rare cases where Ryo kills a target.

Comic Books

 * In one Golden Age Captain America story, a player is murdered on field during a baseball game. Somewhat unbelievably, the game continues with Cap and Bucky subbing.
 * In the A Nightmare On Elm Street: Paranoid comic Freddy kills a boy attending a pep rally by causing him to explode in a mess of blood when he nods off.

Film

 * The Arsenal Stadium Mystery
 * Aversion in The Naked Gun - the Queen is going to be assassinated but Drebin and company save her in time.
 * The Shadow of the Thin Man. Although it's with a horse race.
 * The first reimagined Pink Panther film has the owner of the titular gem being killed at a soccer game.
 * In the film Ronin,, while doing a money-for-MacGuffin-type trade, tries to buy security against a double-cross by having an accomplice threaten the figure-skating girlfriend of the Russian mobster he is making the switch with.
 * Max Zorin and his thugs try to off James Bond during a horse race in A View to A Kill.
 * The main plot of The Last Boy Scout culminates with Bruce Willis and Damon Wayans trying to stop a corrupt senator from getting assassinated at a football game.
 * The movie actually starts with a player (portrayed by Billy Blanks) who was high on PCP bringing a gun onto the field and shooting the oopposing defense's players on the way to the end-zone, shortly before killing himself.
 * Snake Eyes opens with an assassination at a high-profile Atlantic City boxing match.
 * Sudden Death is a terrorist thriller set in Mellon Arena during Game 7 of the Stanley Cup finals.
 * Murder at the World Series, a 1977 made-for-TV film.
 * The movie Two Minute Warning involves a sniper at a Super Bowl-like football championship game.
 * A variation comes at the end of Experiment in Terror, where it's the bad guy who gets shot and killed by cops on a ballfield immediately after a game.
 * A boy is cut in half with a chainsaw just outside a baseball field in Truth or Dare?: A Critical Madness.
 * There are numerous sports-themed slasher films, such as The Catcher, Gutterballs, Devon's Ghost: Legend of the Bloody Boy and The Greenskeeper.

Literature
""For an intelligent murderer, such as you or I might be, it is an impossible plan to make sure that nobody is looking at you."
 * Thomas Harris' novel (and later film) Black Sunday involves terrorists, the Super Bowl, the Goodyear blimp, and a large bomb.
 * Tom Clancy's The Sum of All Fears has terrorists bringing a nuclear weapon to the Super Bowl. In the movie adaptation the President of the United States is also at the game (which is never referred to by name as "the Super Bowl", due to this trope).
 * There was a series of crime novels that literally was based entirely on this trope, titles included Bleeding Dodger Blue, Tigers Burning, Fear in Fenway and Murder in Wrigley Field.
 * Dick Francis' novel Nerve begins with a jockey shooting himself in front of a big racing audience.
 * Father Brown in 'The God Of The Gongs'

"But what other plan is there?"

"There is only one," said the priest. "To make sure that everybody is looking at something else. A man is throttled close by the big stand at Epsom. Anybody might have seen it done while the stand stood empty--any tramp under the hedges or motorist among the hills. But nobody would have seen it when the stand was crowded and the whole ring roaring, when the favourite was coming in first--or wasn't. The twisting of a neck-cloth, the thrusting of a body behind a door could be done in an instant-- so long as it was that instant.""

Live Action TV

 * CSI New York: A man dies after winning a million dollars via a basketball shot.
 * Homicide Life On the Street: A visiting fan is found beaten to death during an Orioles/Yankees game.

Radio

 * A 1939 episode of The Jack Benny Program featured a sketch called "Murder on the Gridiron".

Tabletop Games

 * The opening fight of the Feng Shui adventure "Murderer's Row" in the supplement "In Your Face Again" has the PCs trying to stop a hit attempt on a young girl by the Lotus at a baseball game. The girl turns out to be a MacGuffin Girl whose powers a whole lot of people (those who don't want her dead anyway) want to use for their own ends.

Video Games

 * Both the novel and the game Rainbow Six include a level where terrorists attack the Sydney Olympics.

Western Animation

 * Cotton Hill attempted to assassinate Fidel Castro while he was visiting New York and decided to take in an American Baseball game, a ballgame Hank wound up being born during in the women's restroom.
 * One episode of Ben 10 involves a conspiracy to eliminate the President of the United States and replace him with a robot duplicate. By ambushing him at the Little League World Series. By signing up a little league team comprised entirely of superhuman robots (under the names of famous dead MLB players) and winning the whole season.

Real Life

 * Truth in Television. Has happened many, many times.