Kar Kantar is a Romulan villain introduced in the Star Trek: Picard episode Absolute Candor.
Following the collapse of the Romulan Star Empire after the destruction of Romulus in 2387, Kantar was one of the petty warlords that came to power in the resulting power vacuum. Kantar was one of the individuals running the Qiris sector. He and his people managed to obtain an old 23rd century Romulan Bird-of-Prey that became his mobile base of operations.
When retired Starfleet Admiral Jean-Luc Picard went to the planet Vashti in 2399 to enlist the aid of the Qowat Milat, Kantar's allies on Vashti alerted Kantar that Picard was on the service. Kantar took his ship and traveled to Vashti to confront Picard.
Arriving at Vashti Kantar attacked the ship La Sirena that Picard was traveling on. Even though Kantar's ship was over a century old, it still posed a great deal of difficulty for the La Sierena. With assistance from Seven of Nine the La Sierena was able to sever one of the nacelles on Kantar's ship, disabling it.