Mass Effect players are trying to find fan-favorite asari, Liara T'Soni, in the first installment of the game.
Liara has been a popular choice for both male and female Shepards, alike—likely because she's the only romance in the first game that's open to both make and female Shepards, period. She, herself, is something of an archaeologist and known Prothean-enthusiast. The Protheans have been an integral part of her work since she was very young. Obviously, this means she's one of the best options Shepard has to uncover the mystery behind the visions from the beacon.
In the least spoiler-revealing way possible, here's where players can find her.
Where to Find Liara in Mass Effect 1
Unfortunately, Liara doesn't show up in Mass Effect 1 until a bit later in the game. Shepard first needs to uncover the connection between one of Liara's relatives and the lead antagonist of the first game—a rogue elite operative known as a "Spectre." This will reveal Liara's existence to the Commander and Normandy crew, who figure out her last known location and depart to speak with her.
During a Prothean ruins excavation on the planet Therum in Knossos, a section within the Artemis Tau cluster, Liara and her research team were attacked by the geth. She fled to the deeper catacombs of the ruins and, in an attempt to restart an energy field to keep them at bay, accidentally suspended herself in that energy field. This kept her safe but effectively trapped her indefinitely.
Fortunately, Shepard's team wouldn't take very long to find her—though, if they do, Liara will assume they're hallucinations from her solitary-induced madness. Either way, once freed and safe, she's more than willing to explain her findings and join the Normandy crew.