Mr Bennet is a secondary character in Austen's Pride and Prejudice and important for his relationship with his family and his daughter Elizabeth in particular. He is a flat character since he acts in similar ways even when circumstances change throughout the novel. The most relevant example is his general sarcasm and passiveness; even his youngest daughter's catastrophic elopement with Wichkam does not effect any permanent change in him. He still prefers to reamin fairly aloof concerning family issues.
In terms of his outer characterisation, Mr Bennet owns the Longbourn house and estate which brings the family about £2,000 a year (p. 18). He is married to Mrs Bennet and they have five daughters together. He is also educated and passionate about books.
The inner characterisation of Mr Bennet reveals that he is quite intelligent. However, he is also no longer in love with his (less intelligent) wife and tends to be rather distant with most of his family, with the exception of Elizabeth. About halfway through the novel, Austen gives the readers an explanation of his character and his relationship with his family:
Her father, captivated by youth and beauty, and that appearance of good humour which youth and beauty generally give, had married a woman whose weak understanding and illiberal mind had very early in their marriage put an end to all real affection for her. Respect, esteem, and confidence had vanished for ever; and all his views of domestic happiness were overthrown. But...