If a signal is strictly real and bandlimited below Fs/2, then the DFT results above N/2 are (merely, redundantly) complex conjugates of the below N/2. This is not true for complex signals that are not strictly real (e.g. have non-zero imaginary components), or for signals that are not bandlimited to only containing spectrum below Fs/2.
If, for instance, a complex signal is bandlimited to complex spectrum between 0 and Fs (e.g. contains no negative frequencies), then the DFT result of all the bins, from 0 to N-1, will represent positive frequencies, and there will be no negative frequencies, complex conjugates or otherwise, to alias against the positive frequency data.
Another possibility is for a complex signal to be bandlimited between -Fs/2 and Fs/2, in which case the DFT result bins above N/2 will represent negative frequencies, below 0 at baseband, or below the carrier frequency in the case of complex modulation (e.g. before IQ heterodyne-ing down a strictly real higher-frequency signal that is narrowly-enough bandlimited).