Electron acceptors participate in electron-transfer reactions. In this context, the oxidizing agent is called an electron acceptor and the reducing agent is called an electron donor. A classic oxidizing agent is the ferrocenium ion , which accepts an electron to form Fe(CH).  One of the strongest acceptors commercially available is "Magic blue", the radical cation derived from N(CH-4-Br).
Extensive tabulations of ranking the electron accepting properties of various reagents (redox potentials) are available, see Standard electrode potential (data page).