The Lenarians were an intelligent species.

In 2369, a group of Lenarians attacked a delegation from the USS Enterprise-D before a diplomatic conference, almost killing Jean-Luc Picard with a compressed teryon beam. (TNG: "Tapestry")

This species was only mentioned in dialogue.
It is unclear where this conference took place or what connection the Lenarians had to said conference. According to the Star Trek Encyclopedia (4th ed., vol. 1, p. 459), the crew from the Enterprise-D were "involved in a conference with the Lenarians, when a dissident faction attacked the team."
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