Agent noun of fix: one who, or that which, fixes.
(photography) A chemical (sodium thiosulfate) used in photographic development that fixes the image in place, preventing further chemical reactions.
A person who serves as an agent to arrange for a desired result, perhaps by improper means.
(criminal justice, law) A person who arranges immunity for defendants by tampering with the justice system via bribery or extortion, especially as a business endeavor for profit.
(journalism) A person who assists foreign journalists in volatile countries, often providing interpretation, personal connections, and transportation services.
(real estate, US) A fixer-upper.
(slang) A drug dealer or user.