Mrs. Byrne is Finnegan High's
History Teacher, she is incredibly old, and she only teaches about the war of 1812, despite in one story not even seeming aware there was a war in 1812. She still thinks she is young and beautiful.
Personality
Mrs. Byrne is commonly portrayed as a stereotypical old person, cranky, forgetful, prone to falling asleep, etc. She comanly forgets things, even important things, such as in Mr. Elderman where she forgets she's at a funeral and steals one of the wreaths. She is also often portrayed as strict, and gullible. As well as being well behind with the times, and refering to obsolete technology as if it was still in use, or dead people as if they were alive. She also commonly uses 1930's slang.
Age
A massive recuring gag in the series is her age, she is commonly implied to be ancient, in Mr. Masterpiece she is revealed to have been working at Fingergan high since atleast the 1930's, yet still looks exactly the same. In Mr DNA she had a flashback taking place in 1885, yet still looked exactly the same, placing her age at over 200 years. In Mr. Younger Man she claims to have seen Haley's comet six times already, which would put her between 375 and 456 years old. In Mr. Servant, she claims to have been Miss Constantinople, which puts her age up to at a minimum 558, in the same episode she mentions surving two Crusades in her bunker, which puts here to 763-757, asumming she ment the last two crusades. In Mr. Young, Tater notes this stating "there certainly not a maximum age "(to be a teacher)". In Mr. Tickleschmootz its mentioned she's been alive so long that she has developed immunity to every known illness. In Mr. Shakespeare she's revealed to believe in Ancient Egyptian Mythology, placing here age at over two thousand years. In Mr. 1812, she also believed it was 1812, because it was on the chalkboard.