What is Byronic?

'Lord Byron shone at a period when a school called Romantic was in progress of formation. That school wanted a type by which to mould its heroes,as a planet requires a sun to give it light. It took Byron as that type, and adorned him with all the qualities which pleased its fancy, but the time has more than arrived when it is necessary that truth should reveal him in his true light.'

 Teresa Guiccioli - Lord Byron's Italian mistress  - 'the last attachment'