Althea (also known as Nana) is the maternal grandmother of Ross and Monica Geller. She was mentioned several times on the show but only appeared once in "The One Where Nana Dies Twice", portrayed by Alice Drummond.
Althea (1915—1994) died in "The One Where Nana Dies Twice". After the nurse announced that she had passed and that they could see the body, Ross leaned in to kiss her goodbye and she groaned. He and Monica ran out of the room to find a nurse, telling them and his parents that she "has not passed." By the time hospital staff arrived, Althea had died for real, spurring Ross to bemuse them, his parents and his sister with the line "Now she's passed."
Rachel points out that Monica looks just like Nana. She also had a group of friends similar to Monica's, who hung out at a cafe called "Java Joe's".
Althea acted towards Judy the same way Judy does to Monica. She was very critical of Judy and claimed that nothing was ever good enough. At Nana's funeral, Judy asked Monica if she knew what it's like to "grow up with someone who is critical of every single thing you say?". Despite this, she was apparently close to both of Judy's children.
Althea also had a habit of stealing packets of Sweet 'N Lows from restaurants (and even the Geller's house). While Ross was looking in her closet, he found shoe boxes full of them.
- Nana is mentioned again during the bet between Rachel, Monica, Joey and Chandler in season 4. She is the subject of a question directed toward the guys: "Monica and I (Ross) had a grandmother who died. You both went to her funeral. Name that grandmother!" This is where we learn her real name for the first time.
- Nana is mentioned in "The One With Monica And Chandler's Wedding, Part 2 when Monica is being walked down the aisle by her parents. Judy tells Monica "I wish your grandmother had been alive to see this" to which Monica responds "she's right there" pointing to her grandmother, to which Judy responds "Not that old crow, my mother!"
- Althea is also mentioned in "The One In Massapequa". Apparently, she had witnessed Monica's disastrous, ridiculous attempt at a speech at the 20th anniversary party of Jack and Judy, which had bemused everyone in the Geller family and even drove Judy to "boo (Monica)". After her even more disastrous and ridiculous attempt at a speech at Jack and Judy's 35th anniversary party, which once again bemuses the entire Geller clan, Ross, feeling sorry for his sister, who is clearly upset that her speech did not go well, tried to comfort her by assuring her he thought it was great, claiming that Althea would have loved it, and he believed she was there in spirit, causing Monica to cry. Ross also tells Monica that their parents 40th anniversary he'll make the speech.
- Judy Geller gives Althea's engagement ring to Ross in "The One Where Rachel Has A Baby" to give to Rachel.
- "The One Where Nana Dies Twice" (First and only appearance)
- "The One With The Embryos" (Mentioned only)
- "The One With Monica And Chandler's Wedding, Part 2" (Mentioned only, implied)
- "The One In Massapequa" (Mentioned only)
- "The One Where Rachel Has A Baby, Part 1" (Mentioned only)