Seneca Crane was the Head Gamemaker in the 74th Hunger Games, in charge of coordinating game play and ordering obstacles into the arena. At the end of the Games, he allowed both Katniss Everdeen and Peeta Mellark to emerge as victors, rather than allow them to commit suicide and thus have no victor at all. Unfortunately, this decision did not play well with President Snow, and Crane was dead by the time of Katniss and Peeta's Victory Tour six months later.
In the novels, Seneca Crane is never actually seen, at least not directly. While he most likely observed the tributes' training and demonstrations, as Plutarch Heavensbee did, no physical description of him appears. This is primarily due to narrative mechanics; everything in the novels is seen from Katniss' point of view, and since Crane's name isn't mentioned until Catching Fire, it's possible that Katniss didn't even know who he was until President Snow told her (though the novels are silent on the subject). If that's the case, then she would have had no easy way of recognizing him and mentally cataloging his physical features.
In The Hunger Games film, Crane is portrayed with light skin, light blueish-gray eyes, and dark hair. He sports a uniquely styled beard, shaved in an intricate design, and his hair appears to be heavily styled with product. The film also mentioned that the 74th Hunger Games marks Crane's third year as Head Gamemaker.
The Hunger Games (film)
Prior to the Reaping, Crane was interviewed by Caesar Flickerman about his previous experiences as Head Gamemaker, and what defined his individual style of gameplay. He was also interviewed prior to the Tribute Parade for his opinion of the "recruits" (as Caesar called them): While lacking a fully-formed opinion at that stage, Crane acknowledged that Katniss Everdeen's unexpected volunteering created an interesting turn of events, which could effect gameplay later on.
Throughout the film, Crane met with President Snow to discuss the rising popularity of Katniss Everdeen, as well as Snow's need to keep her (and the districts) in line: After Katniss received an 11 in her training session, Snow questioned the basis for her receiving that score- shooting an arrow at the gamemakers (even though Katniss was actually aiming at the apple in the mouth of a roast pig); what Crane saw as courage Snow interpreted as defiance, and he cautioned Crane that such actions could inspire hope - the only thing stronger than fear - and must be contained. After a meeting with Haymitch Abernathy led to the initial rule change that allowed two victors, Snow discussed the implications of the change with Crane and expressed his opposition to such indulgence.
Despite Snow's opposition, Crane allowed both Katniss and Peeta to live after they threatened to consume poisonous nightlock berries and leave the Games with no victor. In Snow's eyes, this act was the final straw and essentially marked the Head Gamemaker for death. In the book, it is never revealed exactly how Crane died, only that his death was ordered by Snow. In the film, Snow has Peacekeepers escort Crane to a room containing only a bowl of nightlock berries and lock him inside. It is possible that he committed suicide by eating some of the nightlock; in the film of Catching Fire, Plutarch mentioned to Katniss that Crane decided to "quit breathing," implying suicide.
As a result of his decision, Seneca inadvertently paved the way for the rebellion that began in Catching Fire. Had he killed both Katniss and Peeta, the idea of rebellion would have died along with the two tributes. While his granting mercy was likely an effort to save face more than anything, it revealed an unexpected chink in the Capitol's armor; the districts now realized that despite its power, the Capitol could be made to look foolish, and by an underdog at that. Furthermore, Crane's actions ruined one of the primary purposes of the Hunger Games - a reminder to the districts that the Capitol controlled their very existence, and could just as easily have had 24 people rounded up and executed at random, without giving them a chance to fight for their lives. Crane's actions would be repeated by Plutarch, who effectively collapsed the tradition of the Hunger Games when he secretly devised a plan to rescue Katniss from the Arena.
Seneca is first mentioned by name when President Snow revealed that Crane was executed for not killing Katniss and Peeta when he had the chance.
Much later, when Katniss is trying to find some way to rebel against the Gamemakers, she grabs a dummy and ties a noose around its neck, writing the name SENECA CRANE across it. The Gamemakers are shocked and horrified with her performance, and quickly dismiss her.
After Katniss tells Effie Trinket, Haymitch, and Peeta about her performance in front of the Gamemakers, Effie says, "Oh Katniss, how do you even know about that?" This could mean several things; that the news of Crane's death was not widely circulated, that people didn't know Snow was behind it, or simply that they believed whatever story had been publicized about his disappearance (the novels give no specific indication).
Despite being the head Gamemaker in the Hunger Games, and the pleasure he showed in the dangers of the arena (such as his delight in seeing the mutations that were created from the dead tributes) as well as watching people die, Seneca Crane was not entirely evil and showed a degree of mercy by allowing both Katniss Everdeen and Peeta Mellark to survive the Hunger Games. His sentimental streak ultimately led to his execution. He seemed uncomfortable around President Snow, and did not fully agree with the way Snow ruled Panem, but it wasn't until Katniss brought out the berries that would kill both her and Peeta that he finally decided not to go along with everything Snow said.
In Roman history, Seneca the Younger, also known as Lucius Annaeus Seneca, or often just Seneca; a philosopher and playwright. He was well-known in Roman society. He held a seat in the Senate, but later he was exiled. His letters tell us a lot about Ancient Roman lifestyle.