What is the lightest commercial jetliner out there? I was thinking of something like a Embraer E170.
I assume that you want to only compare turbofan-powered aircraft, and exclude aircraft designed to be used as private jets.
In that case, the lightest would be Dornier 328 Jet with a basic operating empty weight of 9200kg, and the next would be Embraer 135 measuring 11402 kg.
It depends on what you mean by ‘jetliner’. By that term I would have to define it as a turbojet powered aircraft which holds a transport category type certificate. A Dornier 328Jet with an OEW of 9420kg would be a good choice. If you consider jets used for commuter operations, a Dassault Falcon 10 at 4400 kg, or an Aerospatsiale Corvette at 3510 kg would be a good choice.