Garson "Gar" Tiernan was a male Human native of planet Deneva in the 24th century. He was a politician who, prior to 2381, served as Vice-President under President Cordaro. That year, when Deneva was alerted of an imminent Borg assault, Tiernan joined over 2700 evacuees aboard the freighter SS Libra, in accordance with emergency protocol Plan 2757. After being out of contact with the rest of the Federation for several days, Tiernan learned that Deneva had been destroyed, at that he was the presumed president of what was left of the Denevan government.
Tiernan intended, shortly after hearing this news, to directly petition Federation President Nanietta Bacco for an accelerated schedule to rebuild his homeworld. However, after witnessing the conditions at the iy'Dewra'ni refugee camp on Pacifica and realizing the overwhelming challenges confronting the Federation, he became resigned to building a new home for his people on planet Ingraham B. (TNG novel: Losing the Peace)
In 2338, he attended the Federation Cup soccer match between Deneva and Bolarus, witnessing Deneva's come-from-behind victory. Tiernan also attended Deneva's Bicentennial World's Fair in 2361. (TNG novel: Losing the Peace)