Everyone of the Q Continuum is called Q, talk about confusing.
In every appearance they have demonstrated almost god-like powers, such as being able to manipulate time and matter at every level and are also immortal. They confuse Federation scientists as they are not what you would expect from such a powerful being.
The main Q played by John de Lancie has been described, in turn, as obnoxious, interfering, arrogant, and a pest. However, underneath his acerbic attitude, there seems to be a hidden agenda to Q's visits that seem to have the best interests of Humanity at their core, although this opinion cannot be proven but everything seems to point this way. I think they know were we are heading and one day may end up like them and this has them worried.
First seen: TNG: Encounter at Farpoint