Laila Morse's EastEnders co-stars call her Mo because she is so similar to her character.
The 74-year-old actress has portrayed 'Big' Mo Harris on the BBC One soap since 2000, and Maisie Smith - who plays Tiffany Butcher-Baker - says all the cast call her by her character name.
Quizzed on which EastEnders' star is most like their character, Maisie said: "I am very much like my character Tiffany, so I am going to say me.
"There are so many things about us that are the same.
There are so many things about us that are the same.
"Actually, no, it has to be Laila Morse - we literally all call her Mo."
Zack Morris (Keegan Butcher-Baker) added: "I definitely agree with Laila and I'm going to say Scott Maslen for the least, because he's nothing like Jack.
"Jack is quite a serious character, but Scott is a bit wild.
"Everybody is kind of funny for different reasons. Scott always makes everyone laugh."
The pair - whose characters are married - joked they bicker "every day" on the soap's set.
Asked if they are like a real-life married couple, Zack said: "One million per cent.
"If I work it out, we spend at least half a day together every day when we're working so that's like 60 hours, which is a lot."
Speaking in a joint interview with OK! magazine, Maisie added: "We literally bicker every day.
"The truth is, we spend a lot of time together.
"Most of my working day is spent with him. To be fair, when we have lunch we do still hang out with each other, but sometimes I'll go to my room and chill on my own."
Mo has become known for regularly delivering comedy one-liners in Albert Square, bringing some humour to the Slaters amid some of their darker storylines.
She was there with some comedy to lighten the mood this week when the Carters' boat party on the River Thames was thrown into chaos when the vessel started to sink.
Referencing film Titanic, she blurted out: "Where's Leonardo DiCaprio when you need him?"