The Swingle Singers were founded in Paris in 1962, and have been through several incarnations since then.
Until 2011, the group consisted of eight voices: two sopranos, two altos, two tenors and two basses. The French group performed and recorded typically with only a double bass and drums as accompaniment. In 1973, the original French group disbanded and Ward Swingle moved to London and hired members who debuted as Swingle II. The current group performs primarily a cappella.
The group later performed and recorded under the name The Swingles, then The New Swingle Singers and The Swingle Singers before settling on The Swingles. The group has never disbanded. As individual members have left the group, remaining members have held auditions for replacements.
The Swingles, under their prior and current names, have a vast output, so large it's impossible to list here. I've selected just a few of their works to give you a taste of their range.
To start with, here's Johann Sebastian Bach's Fugue in G Minor, BVW 578.
Next, Pachelbel's famous Canon.
Here's Rimsky-Korsakov's Flight of the Bumblebee.
Moving on to something much more modern, the Swingles are joined by the Ayoub Sisters in this performance of Astor Piazzolla's Libertango.
Finally, here's an amalgamation of two songs by the Beatles: Blackbird and I Will.
YouTube has many more of the Swingles' songs in their various incarnations.