In The Malloreon, it's revealed how the succession works in Ctholl Murgos: The eldest surviving prince is the heir, and his first royal act is to order the execution of all others. So, all princes are evil, and only the most clever one wins. For example, The Drasnian bastard child.
This was actually the rule in the Real Life Ottoman Empire, and was fine with the populace for several generations until the early death of a sultan resulted in the execution of several child princes. This was a bit much for Turkish sensibilities and after that reign sultans locked their brothers up instead. This proved convenient when the current ruler succumbed without providing an heir.
Several Princes vying for Oberon's throne in The Chronicles of Amber by Roger Zelazny. Describing the exact intentions of the Nine would spoil most of the intrigue, but be prepared that some "evil" guys will be redeemed and some "good" ones will reveal themselves evil to the core.
Miraz from Prince Caspian killed his brother, stole the throne, and plotted to kill his nephew when a son and heir of his own was unexpectedly born.
Wang Sau-Leian in Chung Kuo has to wait for his father and three older brothers to die before ascending the throne - but why wait?
Toyed with in Bujold's The Curse of Chalion. A bare bones description of Royse Teidez slaughtering the sacred menagerie that was keeping the worst effects of the titular curse on Roya Orico's health at bay would seem to fit this trope perfectly, but the boy honestly thought he was eliminating the uncanny source of his older half-brother's illness. The Evil Chancellor's Even More Evil brother, who put Teidez up to it, apparently knew better and was probably trying to supplant his elder brother by replacing the chancellor's puppet monarch with his own. But he dies before his plan can come to fruition.
Prince Festil Furstán of Torenth was a younger son who didn't like being landless, so he gathered other landless younger sons, borrowed some troops from his father and conquered neighbouring Gwynedd in 822.
Then-Prince Wencit Furstán deposed his nephew King Aldred (with the help of Aldred's wife Charissa of Tolan) and took the throne of Furstán for himself.
Prince Conall Blaine Cluim Uthyr Haldane is the eldest son of Prince Nigel Haldane and terminally jealous of his cousin King Kelson and Kelson's foster brother Dhugal, Earl of Transha. He takes secret instruction in using the Haldane powers, which are only supposed to wielded by the reigning monarch. He puts merasha in Dhugal's flask while traveling on a quest for Camber's relics. He seduces the woman Kelson wants to marry. He attacks his father and leaves him in an arcane coma. He ultimately challenges his cousin to a duel arcane at his treason trial. By the way, his second name was also that of a Festillic king; coincidence? Maybe not.
Mahael and Teymuraz Furstán are this (as well as being evil uncles) to Liam-Lajos in King Kelson's Bride. One or both of them are widely suspected of suspected of disposing of Liam's elder brother Alroy previously.
Although based on Macbeth, given that he's the cousin of the king he murders, Duke Felmet of novel Wyrd Sisters likely counts.
This also seems to be played with in the novel Men at Arms where the evil aristocrats try to place Captain Carrot (the legitimate heir) on the throne with Edward d'Eath and other members of the Assassins' Guild as Poisonous Friends.
The Duke of Sto Helit in Mort. Cousin to King Olerve of Sto Lat, he's gone from fifth to second in line before he appears, and becomes next in line shortly afterwards. Described in the Discworld Companion as "quite capable of killing all who stood between himself and the throne, or even between himself and the drinks cabinet."
Forgotten Realms: A Red Wizardess of Thay once magically disguised herself as the queen and seduced Azoun IV, evidently intending to give birth to this trope and seize the throne of Cormyr in a Succession Crisis. Subverted when her agents found out that Azoun had sown so many wild oats as a young man, their Evil Prince would have to get in line behind hundreds of older byblows.
Unsurprisingly, given the title of The Folk of the Air trilogys first book, The Cruel Prince, theres a few in the book:
Balekin and Dain fit the trope quite well, willing to murder family members for the throne. Balekin is an evil prince of the Royal Brat variety, but despite his best attempts is not necessarily a competent schemer. Dain, on the other hand, is a truly Machiavellian Chessmaster.
Cardan inverts this trope. While hes bratty in the first book, he is not at all evil. Hes completely uninterested in the throne and is very loyal to his oldest brother, despite Balekins abuse.
In the first trilogy, Prince Ancar of Hardorn arranged for his father's murder so that he could become king sooner. He went on to be a sadistic bastard, who tortured people for fun, drove his own country into ruin and then invaded his neighbors.
When Prince Thanel of Rethwellan finds out that he can't be crowned king of Valdemar without first being Chosen to become a Herald (which requires being a genuinely nice person), he tries to murder his wife, Queen Selenay, so he can become Regent for their daughter Elspeth.
Prince Robert, the king's brother in Kingdoms of Thorn and Bone, who kills his sister -for whom he has a creepy attraction- in order to lure his brother into a trap. In which he gets killed, but manages to reappear as undead by a fluke.
Kalide from The Legendsong Saga. Hes particularly annoyed given that a) his brother is mad and b) the position of Holder (or mermod) is assigned by the soulweavers, not inherited anyway. Coralyn's plots revolve mainly around bypassing these obstacles to put her preferred (and controllable) son on the throne.
Nightfall (Series): Prince Vladimir is the Big Bad, who has destroyed human civilization and breeds the surviving humans for vampire food.
Old Kingdom: The Greater Dead AdeptKerrigor was originally Prince Rogir, son of the Queen, who became interested in necromancy and Free Magic, and decided to break the Charter (a backbone of the reality of the Old Kingdom) so he could do as he wished without interference. He had his sisters sacrificed to break two of the Great Charter Stones, murdered his mother, and would have killed his half-brother had backup not arrived. He then spent the next two hundred years driving the Kingdom into anarchy, despite various Abhorsens' attempts to stop him, always able to come back thanks to his hidden Soul Jar.
One for the Morning Glory Part of the backstory. The kingdom of Overhill was independent because a king had sent his brother packing to an unsettled corner of the kingdom, and he had declared it an independent kingdom.
The novel The Prisoner of Zenda has an interesting example in the character of Black Michael, who plots to capture and kill his half-brother, the legitimate heir and take the throne for himself. Uniquely, he is much more popular than their true heir, suggested to be their father's favorite and doesn't come across as that evil outside of this plan.
Ranger's Apprentice - Halt is the older of a set of twins. His brother drove him from their native kingdom to take the throne for himself.
Robin Hobb's Realm of the Elderlings: Prince Regal from the Farseer trilogy fits this quite well. He's born the third son of the king. After Fitz appears and Prince Chivalry (the eldest) steps down, he bides his time for a while before sending Verity (the middle Prince) off on a suicidal mission (and sends some Mooks to make sure he doesn't return), and finally offs the king right after being confirmed as the King-in-Waiting.
Redwall has both Evil Princes and Evil Princesses. In Mossflower Tsarmina Greeneyes usurps the throne from her brother (displaying ultimate ignorance of point #3 in the Evil Overlord List), and in Marlfox various members of the seven offspring of the titular villainous royal family are constantly attempting to backstab their siblings and mother. Then there's Kurda, another female example, and her brother Bladd in Triss, Pitru in High Rhulain, Klitch in Salamandastron and possibly Veil in The Outcast Of Redwall... though his father, Swartt, is a lord not a king.
Prince John, from the most widely accepted modern version of the Robin Hood stories (and, according to some, in Real Life, although the latter has been hotly contested among reputable historians on both sides). (Please see the Discussion Page for further details.)
Conphas, the crown prince of the Nansur Empire in Second Apocalypse, is incredibly vain and duplicitous as well as a master strategist.
In Tolkien's The Silmarillion we have Ar-Pharazôn, last King of Númenor, who usurped the throne by the less usual method of marrying the rightful heiress (who was also his cousin, despite it being illegal under Numenorean law) and then forcibly reducing her role to that of his consort. There's also the example of Maeglin, the nephew of King Turgon of Gondolin, who betrays the city to Morgoth partially to gain rulership over it, but mostly because he wants to marry his cousin. That she already has a husband and son doesn't stop him — he just plans to off them first.
Evil and arrogant Viserys Targaryen fits this trope, if only because he believes himself the rightful King of the Seven Kingdoms and behaves very much like one, despite not having a kingdom and being actively disliked by most if not all people who come into contact with him. It's pointed out his actions may be because spending most of his life in exile, basically as a beggar, has twisted him, as his sister Daenerys remembers he used to be nicer.
Joffrey Baratheon... isn't this. Yes, he's evil, and yes, he's a prince, but he wants Robert's approval. Though he's fairly dismissive of Robert after his death. By that point though, Joffrey's an evil ''king''.
Ramsay Snow plays aspects of this straight, though his father is a Lord, not a King. He poisoned his kind-hearted half-brother Domeric Bolton, betrays the Northern forces, then betrays the Ironmen and sacks Winterfell. He's also a Sadist who delights in practicing the old Bolton custom of flaying. His father Lord Roose Bolton, is quite evil himself, being a sociopath who sired Ramsay through rape, and murdered his King Robb Stark at The Red Wedding, but Ramsay is much worse and less subtle about his evil, and is believed by many to be the most evil character in the series. When Roose thinks Ramsay has died he says his trueborn children would never have been safe with Ramsay. He ends up legitimizing him to Ramsay Bolton but mentions that Ramsay will probably kill any future children that could threaten his claim.
Stannis is seen as this by much of the Seven Kingdoms, who believe he is trying to usurp the IT from his brother's children and concocted the rumors of their illegitimacy to justify this. In reality the rumors are true and Stannis doesn't want to be King, but believes it's his duty to become King as by the succession laws of the Seven Kingdoms he is Robert's heir. While still a bit of a jerk he does go through Character Development after he is defeated at the Blackwater and starts becoming a more likable figure.
Euron "Crow's Eye" Greyjoy, who is suspected of having his brother Balon Greyjoy assassinated so he could become ruler of the Iron Islands and is implied to have molested his youngest brother Aeron "Damphair", along with raping or seducing another brother Victarian's wife, meaning Balon exiled him from the Isles. Aeron, a Priest of the Drowned God, calls a kingsmoot to try making sure Victarian becomes King, as Balon's sons are believed all dead and though Balon wanted Asha to succeed him Aeron doesn't think a woman can rule. Unfortunately Euron gets the support from the Kingsmoot to become King by revealing his plans to conquer the Seven Kingdoms. Asha's maternal uncle Rodrik Harlaw immediately tells her to flee the Iron Islands, fearing Euron will have her killed.
Aerion "Brightflame" Targaryen, who Viserys takes after. He is cruel and pyschotic, and a Big Brother Bully to Aegon, threatening to castrate him. Aerion is cruel to animals, throwing Aegon's cat down a well and killing a horse during a joust, for which his uncle Baelor disqualifies him. In anger, Aerion attacks a Puppeteer just because their show has a dragon (the Targaryen sigil is a dragon) getting killed. Thankfully he predeceases his father Maekar by a year, meaning Aegon becomes King.
Maegor the Cruel, considered the cruelest King to ever sit the Iron Throne. He beheaded the Grand Maester who pointed out his brother's son should succeed instead of Maegor, had two of his nephews killed, and performed numerous atrocities in and out of his war with the Faith. When the realm united under his last nephew Jaehaerys, Maegor died mysteriously, possibly killing himself using the blades of the Iron Throne,
Prince Daemon, from over a century before the books, brother of Viserys I, known as "the Rogue Prince". He was a pirate and had an affair with his niece Rhaenyra, for which his brother exiled him. He finally married Rhaenyra, taking her side when she tried to take the throne from her half-brother Aegon II after her father's death and is thought of as The Corrupter to her. When one of his stepsons was killed he had one of Aegon's infant sons murdered. However, he never tried to usurp the Iron Throne and Rhaenyra had been named by Viserys as his heir, but Daemon still comes across as a complete jerk as he was basically trying to gain power any way he could, even if never in a pure "usurpation" sense. Aegon II could be considered this trope, depending on who's telling the story, as he went against his fathers wishes in taking the Iron Throne himself, even though the laws of succession favored him. He did feed Rhaenyra to his dragon when he captured her and when the war turned against him tried to have her son Aegon killed out of spite, but was poisoned before he could do so. Rhaenyra can be considered the rightful heir, but proved to be quite a tyrannical ruler herself, such as in her treatment of the dragonseed and imprisonment of her father-in-law Corlys Velaryon. As a result she is largely responsible for ruining the chances of any woman sitting the Iron Throne.
Daemon's youngest son Viserys II is believed to have poisoned his nephew Baelor the Blessed. However, it is believed by many that Baelor actually died due to his excessive fasting. In the main series, set over a century later, Tyrion says that even if Viserys did murder Baelor, he had been running the Seven Kingdoms as Hand during their reign, and may have done this for the good of the realm, considering Baelor certainly seems to have insane in a religious manner. Ironically, it is suspected Viserys sudden death a year later was due to his son Aegon IV "The Unworthy", one of the worst Targaryen Kings, poisoning him.
Daemon Blackfyre, a legitimized bastard of Aegon IV and his cousin Daena Targaryen, who tried to usurp his half-brother Daeron II. He may have been acting in accord with his father's wishes, though, as Aegon didn't get on with his only legitimate son, and may have begun the rumors Daeron was really the son of Aegon's brother Aemon so he could name one of his bastards as heir. Daemon's descendants continued during to usurp the Targaryen Kings for generations afterwards before their extinction (at least in the male line).
Another of Aegon's bastards, Aegor Rivers "Bittersteel", seems to have encouraged Daemon in his attempt to take the Iron Throne and remained trying to assist the Blackfyres for the rest of his life.
Another of Aegon's bastards Brynden Rivers "Bloodraven" plays with this. He's a rather morally ambiguous character and kinslayer who is thought of as a sorcerer and Evil Chancellor who turned the Seven Kingdoms into a Police State with his network of spies. Eventually he was even sent to the Wall for killing a Blackfyre after offering them safe conduct, showing even the Targaryens found his methods too extreme. However his killing of Daemon Blackfyre and two of their sons helped win the battle of Redgrass Field and defeated the first Blackfyre rebellion. And though he certainly seems to have been a skinchanger many of his ruthless methods seem to have been necessary in preventing the very real threat of the Blackfyres.
Daeron's fourth son Maekar I is believed to be this by much of the Seven Kingdoms, due to him killing his well-liked eldest brother Baelor in a trial by combat, though it was an accident and Maekar is genuinely upset about this. His youngest son Aegon even hears other squires saying Maekar means to murder both his other brothers and nephew. Ironically enough Maekar does end up as King, though unintentionally, and remains permanently upset because of Baelor's death.
A minor case is Tywin Lannister's grandfather, Ser Gerold Lannister, who is suspected of murdering his brother Tybolt Lannister and niece Cerelle Lannister so he could become Lord of Casterly Rock.
Arnolf Karstark, Lord Rickard Karstark's uncle and Castellan of Karhold, declares for Stannis hoping Rickard's last son Harrion, a captive of the Iron Throne and Lord of Karhold after his father's execution, will be executed for this, after which he intends to force Harrion's sister Alys to marry his son Cregan, enabling his branch of the family to take control of Karhold. Arnolf is also working with Lord Bolton to betray Stannis. His hunchback, plan to have his (great-)niece marry her "uncle", and the Karstark sigil and words "The Sun in Winter" mean he is likely based on the theatrical Richard III (ironic considering that some of the most popular and more heroic characters in ASOIAF are also based on Richard III).
The Freys, one of the most despised Houses in the series, possibly have a few. Lord Walder Frey has over a hundred descendants, and some of them are plotting to move their way up in the line of succession, meaning by the time the 91-year old Lord dies his House will collapse into war. One of Walder Frey's great-grandsons, "Black" Walder Frey, is suspected by his elder brother Edwyn Frey to be behind the death of their father Ryman Frey, though in reality Ryman was hanged by outlaws, moving Black Walder a step closer to inheriting the Twins. There's even a fan theory Black Walder was behind the death of his grandfather, Walder Frey's oldest son and heir Ser Stevron Frey. Walder Frey's ninth son, Merrett Frey, even thinks that the 12th son, his half-brother "Lame" Lothar Frey, may be more dangerous then Edwyn and Black Walder.
A grandson of Walder Frey and full nephew of Lothar, "Big" Walder Frey, is only nine years old but already seems to be becoming this, claiming he'll be Lord of the Crossing despite being low in the line of succession (his father Jammos is the 13th son). He is probably behind the murder of another of Walder Frey's grandsons, "Little" Walder Frey, who was 52 days younger then him. Big Walder still comes across as quite sympathetic, as his cousin was a bully who was becoming more sadistic while squiring for Ramsay, and shows a nicer side in regards to Theon. Says a lot about the Freys that a Token Good Teammate of theirs is a kinslayer.
Dagnarus of the The Sovereign Stone trilogy was second in line for the throne. He didn't hate his father or try to take the throne away from him, but he did both for his elder brother, Helmos.
All the princes in Stardust (except possibly Primus), but especially Prince Septimus. Moreover, their father was himself an example of The Evil Prince made good, as were a number of other monarchs before him (it was a family tradition). Primus, while clearly ambitious, appears not to be evil (to stop Septimus, Primus bribes a soothsayer to lead his brother on a wild goose chase; to stop Primus, Septimus tries to poison him).
In the book, each of the three princes that survive their father (including Primus) had killed one of their brothers; Septimus had killed two. Before the book ends, Septimus had killed a third and was quite peeved that someone had Primus killed first as he now had to avenge his dead brother instead of kill him.
In the book, the father is quite peeved at the inadequacy of this generation: his father had been, properly, down to one son by the time of his death. He says as much in the movie as well and helps arrange for Septimus to off another one before he dies.
Star Wars Legends: Prince Xizor from the Shadows of the Empire multimedia project qualifies. Whether "Prince" might just be the title given to him for being the head of Black Sun, he sits at the Emperor's feet and has a bitter rivalry with Darth Vader for Palpatine's favor.
Xizor was a prince to the Falleen, his own race. However, the majority of his race, including his family, were accidentally killed by Vader. He secretly planned to murder the Emperor and Vader, though he suspected, and it was confirmed, that Palpatine was well aware of this and kept him around since he was useful and he felt that any of Xizor's plans would fail.
Extremely rare female example in the Trickster's Duet; Princess Imajane, the regent for the four-year-old king, arranges to send a magical storm to kill his majesty and become queen. Her husband doesn't object, but he's mostly following her lead. Surprisingly, it works. For a while.
A minor example in Beka Cooper. Prince Baird is a Jerkass and willing participant in the plot against his brother, but he's really a pawn of Lord Halleburn and wouldn't have come up with the idea on his own.
In Vampire Academy, Victor Dashkov is a prince, the head of the royal Dashkov family. Formerly, heir to the throne - if it weren't for his health. He schemes to get the throne and does not care who gets hurt in the process.
In Shards of Honor, Prince Serg was sufficiently nasty that his father was forced to kill him rather than let him succeed to the throne.
A subplot in A Civil Campaign deals with this on a lesser scale. Richars Vorrutyer had done everything up to and including possible murder to ensure his cousin Count Pierre died without issue and left him the heir apparent. He thought Pierre's younger sister Donna using an old rule to secure a three month stay on his confirmation and heading offplanet before the late Count was in the ground was of no consequence... and was rather put out when Pierre's younger brother Dono returned to Barrayar to claim said seat by right of blood.
In Dan Abnett's Gaunt's Ghosts novel Necropolis, part of Salvandor Sondar's Back Story; he killed his uncle to gain his place and still resents how much his uncle was loved.
In Dan Abnett's novelBrothers of the Snake, when the Space Marine Priad is told that a queen was murdered, his immediate suspect is the new king. The Inquisitor, who told him, tells him that he is no detective.
Luc apparently thought he was going to be the king of Andor, despite it only ever having Queens. Luckily, he mysteriously disappeared before this could happen.
This kind of succession seems to be standard in Seanchan. The Empress's children are expected to contend with each other, so only the fittest can inherit the throne. It's not clear whether the Empress herself is a target from this.
In The Witchlands, Merik is convinced his sister is one, as he believes she tried to have him killed to make sure she can get to the throne, and cares for nothing but her ambition. Eventually, it turns out she's just as devoted to Nubrevna as he is and has nothing to do with the assassination.