There are about a dozen extensively investigated high-mass X-ray binaries (HMXBs), including LMC X-4, Cen X-3, 4U 1700-37, SMC X-1, Cyg X-1, and Vela X-1. Bhattacharya & Van den Heuvel (1991) compiled a list of “standard” HMXBs (see table 8 of their review article) and most of them, except for Cyg X-1 and 4U 1700-37, are accreting X-ray pulsars with an early-type or a Be star companion. Cyg X-3 was long considered to be a low-mass X-ray binary (LMXB). It was, however, recently revealed from infrared observations that the companion star has characteristics of a Wolf-Rayet star and it may be a fairly massive helium star (Van Kerkwijk et al. 1992; Van Kerkwijk 1993). I shall review here some recent progress in observational studies of the “standard” HMXBs and Cyg X-3.