Until 1990, Croatian Radiotelevision (HRT) was called Radiotelevision Zagreb (RTZ). It was a part of Yugoslav Radiotelevision (JRT).
It was first planned to rename RTZ to HRTV, but this version was never used.
1990-2006, 2000-present (secondary logo)
In June 1990, the Croatian Parliament renamed RTZ to HRT. In 1993, HRT became a full member of EBU. The first version of the logo was black. Though this version is related to the HRT satellite channel, there's still a possibility that it was aired on normal channels, mostly HRT1. Again, since the number of the channel is not specified, most probably used to air on HRT1 and 2.
By 2000, this logo is still remaining in use as a secondary logo.
In 1998, the logo became grey and the two red cubes were animated. This variation only appeared only in idents and it's official website.
2000-present (primary logo)
On October 5, 2000, the logo is now slightly different, but its previous logo from 1990 is dismissed from being the main logo and is now still in use as a secondary logo.