 Two long-term transitions were the transfer of Worf and Miles O'Brien from permanent characters on "The Next Generation" to permanent characters on "Deep Space Nine".Worf stayed on "The Next Generation" until its conclusion, then transferred from the start of season 4 of "DS9".Chief O'Brien had appeared in fifty episodes of "The Next Generation", but only gained opening credits billing on "DS9", in which he appeared in almost every episode of all seven seasons.