Walter White from Breaking Bad. Interestingly enough, his name was chosen because it sounded so plain and unassuming.
Brooklyn Nine-Nine has this apparently be a form of Author Appeal for Detective Peralta. When making up characters for he and his Captain to play, he names them Bret Barley and Gerald Jimes (he even says Jimes' fake dead wife is called Jane Jimes).
There are surprisingly few in Game of Thrones, given the Loads and Loads of Characters: Sansa Stark, Podrick Payne, Lancel Lannister, Salladhor Saan, Mandon Moore, and Boros Blount. Lancel's name is even lampshaded when Robert asks if he was named by a half-wit with a stutter.
Sue Sylvester note which, considering her parents are Nazi hunters, is a bit of Fridge Brilliance in itself considering her initials are "SS" and Artie Abrams from Glee, as well as Holly Holiday, Sebastian Smythe and Azimio Adams (and Quinn's mentioned sister Frannie Fabray). And Jesse St. James, if you omit the "St." in his name.
From Gossip Girl, there's initially only Bart Bass, Chuck's father, and Anne Archibald, Nate's mother. Later seasons introduces more alliteratively-named characters: Damien Dalgaard, Rick Rhodes, Agnes Andrews, Bree Buckley...
The villain's real name is Gabriel Gray. Peter Petrelli and Gabriel Gray are the only powered characters in the series to have these alliterative names. They also seem to be set up as nemeses. They are also the only two characters who have multiple powers, although for different reasons.
Richard Drucker, who's a half-step from Dick.
As of season 4, there is Samuel Sullivan.
Hindsight: Becca Brady's best friend is named Lolly Levine.
The live-action Incredible Hulk series had Robert Bruce Banner (sort of) renamed David in order to invert this trope.note His full name is ultimately revealed to be "David Bruce Banner", but is referred to as simply David.
The IT Crowd: Maurice Moss. He's mostly referred to as just Moss.
The Oni in Kamen Rider Hibiki exhibit Alliterative Names, at least when their names are transliterated into romaji. As an added bonus, the main characters' names seem to line up with their titles (if you wrote them out in kana, they all have the first same sound)
Hibiki: Hitoshi Hidaka
Ibuki: Iori Izumi
Zanki: Zaoumaru Zaitsuhara
Todoroki: Tomizo Todayama (although he was originally meant to take the Zanki title as well, but decides that he needs to define his own path)
Keeping up with its comic book origins, has Lois Lane, Lionel Luthor, Lana Lang, Lucy Lane, and Lex Luthor (though his first name is actually short for Alexander). The Luthor tree also gets another one after The Reveal that Tess Mercer was born Lutessa Lena Luthor.
Alec Abrams/ Stephen Swift, Cassandra Carver, Graham Garrett, Linda Lake, and Maggie McDougal
The Swedish advent calendar Superhjaltejul had quite a few. Supersnällasilversara, Järn-Jerry (though slightly justified as these are both the names of superheroes, and superheroes tend to have these quite a lot), Frigolit Fragile, the Tinnitus Triplets, Flemming Flinků
Switch! parodied the ZDF News' most senior broadcaster duo, who are called Claus Kleber and Gundula Gause, just as many other Germans did. Needless to say, their interaction in the parody is equally rhyme-ridden.