As one of the most visible Romulan leaders along the Neutral Zone of the 2360s, Tomalak enjoyed playing the role of a sneering, calculating diplomatic soldier for his elusive people. Tomalak matched wits with Starfleet's Jean-Luc Picard three times over the years, and was outmaneuvered on each occasion. In 2366, he had to back down after a spy craft that violated the NZ was discovered on Galorndon Core, and he was later surprised when plans to expose his own service's Admiral Jarok as a traitor (with a fake invasion story involving Nelvana III) were quelled when three Klingon ships decloaked to back up the Enterprise-D.

In his last known appearance, in 2370, he confronted Picard during incidents surrounding a Q-created, alternate-future timeline.