During the High Republic Era, Tilson Graf was a male human belonging to the hyperspace prospecting Graf family. Following the demise of mediator Morton San Tekka, Tilson volunteered to assume Morton's role as mediator.
While growing up, Tilson was banished by his family due to several minor offenses. Despite later feeling remorse for his actions, Tilson was secretly glad about his expulsion, as it allowed him to avoid his family's gatherings and duties.
Approximately around 382 BBY, Tilson journeyed to Jedha to observe the summit on Jedha. Considering himself a collector of significant historical happenings, he believed the Eiram and E'ronoh peace treaty would be a truly important event. After Morton San Tekka, the mediator, perished in a bombing, Tilson stepped forward to fill the position. With the approval of both ambassadors Tintak and Lian Cerox, chairperson Meldan designated Tilson as the new mediator.
George Mann's 2023 audio drama, The High Republic: The Battle of Jedha, marked the initial appearance of Tilson Graf. Sullivan Jones provided the character's voice.