Franklin Roosevelt. He was responsible for the "New Deal" politics which began the march toward the current entitlement programs and the beginning of Socialism in the U. S. government practices. Other than several welfare programs which are the legitimate offspring of the "New Deal" legislation, three banner programs still survive.
Although most regulations on businesses have been repealed, the regulation of Wall Street by the Securities and Exchange Commission is still in place. Also, the Federal Deposit Insurance Corporation, established in 1933 still guarantees the funds of depositors up to $100,000. This program was established by fear of another bank run like was seen in 1929.
The last major program to touch on is Federalized "Social Security", a misnomer if there ever was one. As distributed today, it offers no security whatsoever, nor even the normal return on monies invested. Erroneously labeled as an "entitlement", it is no such thing. An entitlement is monies paid out for distressed families, such as welfare, food stamps, or WIC, monies that exist for no investment on the part of the individual receiving the funds.
Social Security is monies repaid for monies invested, although anyone on Social Security will tell you there is no chance of getting even an equal return on monies paid in due to mishandling of these funds by Congress. This is why there is a cry for privatized Social Security, based on sound investment practices, but don't hold your breath. Congress never willingly gives back your money when it already has it.