1P/Halley has been observed reliably at every return since 240 BCE: a total of 30 apparitions over 2,261 years. Over this time, there is a long sequence of Chinese observations, ranging from brief notes to quite detailed descriptions including tail length and colour. However, due to small long-term perturbations of the orbit that affect the visibility at perihelion, there is no plausible observation of 1P/Halley prior to 240 BCE. Of 24 known instances of comets approaching Earth to within 0.1 astronomical units, three are historical apparitions of 1P/Halley. As the Chinese observations are pre-telescopic, the duration of naked-eye visibility gives us interesting insights into changes in its intrinsic brightness over this time. This paper examines the very close-approach apparitions of 374 CE, 607 CE and 837 CE and 1066 CE, as well as various returns of either historical importance, or for which there is evidence of brightness anomalies. Special attention is given to the 607 CE return, at which observations of 1P/Halley are mixed with those of at least one additional comet seen later in the same year. It is suggested that 1P/Halley was genuinely exceptionally bright in 1066 CE, but that the unusual duration of visibility in 1145 CE and in 1301 CE was more likely to be due to errors in the historical record. The 1910 CE return is found to have been more than a magnitude below average brightness, but that of 1986 CE was anomalous: although 1P/Halley was unusually bright pre-perihelion, the combination of a below-average return and poor observational circumstances led to the faintest maximum brightness recorded for any observed return.