—Marth discussing his mother's death in Chapter 17 of Shadow Dragon.
Liza is a character mentioned through dialogue in Fire Emblem: Shadow Dragon and the Blade of Light and Fire Emblem: Shadow Dragon, but never seen in the games. She is the mother of Marth and Elice, the wife of Cornelius, and the queen of Altea.
Liza was captured alive along with her daughter Elice in the Dolhriran and Grustian assault on Altea. Liza and Elice were under the jurisdiction of General Camus, when the Sable Knight fell out of favor with Medeus for his safeguarding of Nyna, the Mage Dragon Manakete Morzas replaced Camus as overseer of Altea castle and Liza's jailer. Liza was personally killed by Morzas who thereafter handed Elice over to Gharnef.
During Marth's retaking of Castle Altea, Morzas taunted Marth over Liza's death. When the battle was over, Marth had little time to mourn due to his new duties over the freed Altea.
She is only mentioned in the games, but she did make cameo appearances in the manga adaptation where an illusions of her and her husband appeared before Marth as part of a plan of Gharnef to dissuade the Prince.
In the first episode of the anime, Liza appears in a flashback, calming down Cornelius after he disciplines Marth.