Short answers, pulled from the story.
Charles VIII was King of France from 1483 to his death in 1498. Known as "the Affable," he came to the throne at thirteen after his father Louis XI died, ruled initially under the regency of his sister Anne of France, and is best known for launching the French invasion of Italy in 1494.
Charles invaded Italy to press his dynastic claim to the Kingdom of Naples, a right inherited from René of Anjou through his father Louis XI. He was further prompted by an invitation from Ludovico Sforza, Duke of Milan, who sought French support against Pope Alexander VI. Charles secured his borders with three treaties before crossing the Alps in September 1494 with 25,000 men.
Charles VIII died on the 7th of April 1498 at the Château d'Amboise after reportedly striking his head on a door lintel while walking to watch a jeu de paume match. He fell into a coma around 2:00 in the afternoon and died nine hours later. A 2021 study challenged the traditional account, proposing instead that he died of severe brain injuries possibly linked to an epileptic condition caused by neurosyphilis.
Charles married Anne of Brittany in December 1491 at the Château de Langeais, making him administrator of the duchy and creating a personal union with France. Anne had previously arranged a proxy marriage to Maximilian of Austria, but the French army invaded Brittany and forced her to renounce that union. The marriage also followed Charles's cancellation of his prior betrothal to Margaret of Austria, who was finally returned to her family in 1493.
At Fornovo in July 1495, the League of Venice attempted to prevent Charles from returning to France after his conquest of Naples. The League lost around 2,000 men to Charles's roughly 1,000, but Charles lost nearly all of the campaign's plunder. He crossed back into France successfully, though Aragonese forces recaptured his remaining garrisons in Naples on the 6th and the 7th of July 1495, leaving him with no lasting gains from the Italian expedition.
Louis XII succeeded Charles VIII in 1498. He was Charles's second cousin once removed and brother-in-law, from the Orléans cadet branch of the House of Valois. Charles had no surviving male heirs; all six of his children with Anne of Brittany predeceased him, making Charles the last king of the elder Valois line.