These are some characters I've created mainly for my Trolls AU in which there are seven tribes instead of six, kind of like the seven stars in some Mario games. Yes, I invented my own troll tribe. That might not be conceptually the same thing, but anyways, here are Benny and Martha.

King Benny and his sister Princess Martha are the leaders of the swing music trolls. They are similar in appearance to the rock and pop trolls because that's how swing trolls normally look. Benny has very light blue skin and a dark blue nose, and his hair is neatly combed and split into two shades of blue on each side. His eyebrows are also split, and his eyes are like green. He wears a white shirt with puffed sleeves and a mauve tie with an old-fashioned taupe vest over it, plus a pair of taupe pants and some black and purple dress shoes. Martha has indigo skin and white hair in a neat style that resembles a snowman, and she wears light blue eyeshadow in a cat eye design. She also has light green eyes, and she wears a blue tiara, plus an old-timey dress that's cut out in a spike pattern on the collar with puffy blue-green sleeves and a cerulean belt, and also a pair of whitish-blue heels with blue and green stones on them.

Benny and Martha are very cooperative with one another, and they're both polite and well-mannered. Benny is a pretty chipper fellow who's known for his natural charm, and Martha is peppy, energetic and emotional. She's also very sweet and pretty like an old female jazz singer, whereas Benny has the attitude of an old radio host, talking in a hearty and fast voice. Benny and Martha like to do things together, which is why they both rule the swing kingdom, Mt. Big Band. They also really love to dance and sing as a pair.

King Benny is open to meeting new people, and Martha is too. When they first heard about Queen Barb's world tour, Benny thought that it could be some new material for his radio show until he and Martha learned she was there to take the swing string. After the conflicts were resolved, though, the royal siblings found something even better, which was a world full of wonderfully different people. Martha and Benny love hanging out with the other leaders, and they've found that they're fun to collaborate with. A certain techno king, for example, worked with them to create a fun electro-swing sound...

In this AU's version of World Tour, Poppy and her pals pay a visit to their home, Mt. Big Band, where they try to warn King Benny about Barb's plans to destroy them. The other swing trolls were pretty confused by how noisy and sparkly they were. When they found them, Benny and Martha were feeling a bit down because they'd already gotten suspicious of Barb's whole world tour thing. Benny's still a pretty optimistic guy, though, so he greeted the pop trolls with a sense of hope that they'd be able to fix things. So, he and Martha wished them good luck. After that was when the pop gang started heading over to Lonesome Flats. 

King Benny and Princess Martha are the leaders of the swing music trolls, who like the jazzy side of music. They enjoy music with flaring trumpets, a jumping rhythm and saxophone riffs that you can twirl to with a partner. When Benny became king, he wanted to include his sister when ruling over the kingdom because the siblings had always liked doing things together, so they lead as a pair. They live in a swanky mansion in a town situated atop Mt. Big Band, which is reminiscent of a city in the 1930s-40s. There's a huge plaza where the citizens gather for parties and events. They live in apartments and houses, and they dress very neatly. They like to listen to radio shows, especially Benny's, which he has an entire room in the mansion dedicated to. Martha thinks that the mansion wouldn't be complete without her powder room, which she spends her mornings getting spiffed up in. If you want an idea of how old-fashioned Mt. Big Band is, there are newspapers, jukeboxes, rubberhose cartoons and a lot of vintage decor.

I imagine Martha having a pretty soft voice, and she's also really good at scatting, so I think her headcanon voice actress would be Caro Emerald. As for Benny, I imagine a voice that matches up to his talk show host attitude, but I can't think of anyone well-known enough...