A trading species who visit Deep Space 9 regularly, are trusted commercial partners of the Cardassians, and whose central bank was famously robbed of latinum on Mother's Day in 2365.
The Lissepians are a merchant species often seen or mentioned around Deep Space 9. The Cardassians regard them as dependable trading partners, and their freighters pass freely through Cardassian space.
In The Homecoming, Kira and O'Brien disguise the runabout Rio Grande as a Lissepian transport in order to reach Cardassia IV. In The Maquis, Part II, Dukat admits that Lissepians have been used to carry weapons to Cardassian colonists, though they are caught more often than the Xepolites. A Lissepian supply ship attacked by the Maquis draws Kira and Odo away in Heart of Stone.
Who Mourns for Morn? reveals that Morn and four accomplices stole a thousand bricks of gold-pressed latinum from the Central Bank of Lissepia. In Bar Association, Quark buys a faulty Lissepian programme for holographic waiters.