Hertzsprung–Russell diagram of the WN stars in the LMC (adapted from Hainich et al. 2014). The filling color reflects the surface composition (red: with hydrogen; green: hydrogen-free), while the symbol shapes refer to the spectral subtype (see inlet). The labels refer to the BAT 99 catalog numbers (Breysacher et al. 1999). For comparison, the Galactic WN stars studied in the present paper are represented by the grey (hydrogen-free) and black symbols in the background. For orientation, the ZAMS are indicated for solar composition and for pure helium stars, respectively.