James Sadleir (c. 1815 – 4 June 1881) was a member (MP) of the British House of Commons, chiefly notable for being one of the few members expelled by that body. Sadleir was the son of Clement William Sadleir of Shrone Hill, County Tipperary. His brother John, with whom he was involved in the Tipperary Joint Stock Bank, was MP for Carlow Borough from 1847.
James Sadleir was approached to stand as a Liberal candidate for the Tipperary constituency in the 1852 election and initially refused, but was eventually induced to accept; he was formally nominated by the incumbent, Nicholas Maher, and was elected easily.
He supported the idea of religious equality in Ireland, although without much enthusiasm for the Roman Catholic priests in his county who passed a vote of censure in April 1853. His brother served in Lord Aberdeen's government as a Junior Lord of the Treasury from December 1852 to January 1854 when he resigned, having been implicated in an attempt to imprison a depositor of the Tipperary Joint Stock Bank who had refused to vote for him.
The scandal that led to both of their downfall arose through the crash of the Tipperary Bank in February 1856. The Bank's London agents, Glyn and Co., refused to pay on draughts of the bank, returning them with the words "not provided for". The Bank of Ireland continued to pay as usual for a week more, resulting in a rush of investors withdrawing their money there. Then, on 17 February, John Sadleir, who had been the principal creditor of the bank, committed suicide on Hampstead Heath. He sent a suicide note to James' wife Emma which read "James is not to blame–I alone have caused all this dreadful ruin. James was to me too fond a brother but he is not to blame for being deceived and led astray by my diabolical acts. Be to him at this moment all the support you can. Oh what I would not suffer with gladness to save those whom I have ruined. My end will prove at least that I was not callous to their agony." It was found by the Irish courts that John Sadleir had begun to abstract money from the bank from about the end of 1854, and took a total of £288,000.