Big Rocky Planet aka super-Earth
The maximum limit for a super-Earth-size planet —an extrasolar, rocky planet— is estimated to be around 5-10 Earth masses* and 2 Earth radii, beyond which the gravity becomes significant enough to hold hydrogen in the planet’s atmosphere, leading to the formation of a gas giant.
It is difficult to establish the largest super-Earth, probably, among those known, the primacy belongs to HD 69830 b, since it is about 10 times more massive than Earth. Some other curiosity: the first super-Earth was discovered in 1992, while the first super-Earth around a main sequence star (the red dwarf Gliese 876) was discovered almost fifteen years later. It was Gliese 876 d, who has a mass approximately 7.5 times that of our planet. Thereafter —mostly thanks to the mind-blowing Kepler mission team— they began… comin’ outta the goddamn walls!
For those of you wondering about the size limit for a gas giant, it is about 15 Jupiter masses**, beyond which the pressure is enough to start the deuterium burning, a nuclear fusion reaction typical of brown dwarfs.
*Earth mass (M⊕) = 5.97219 × 10^24 kg.
**Jupiter mass (MJ or MJUP) = 1.8986×10^27 kg.
1 M⊕ = 0.00315 Jupiter masses.
Asked by gravitonquark