GDRT (also GDR, vocalized by historians as Gadarat) was a King of the Kingdom of Aksum (c. 200), known for being the first king to involve Axum in the affairs of what is now Yemen. He is known primarily from inscriptions in South Arabia that mention him and his son BYGT (also vocalized as "Beyga" or "Beygat"). GDRT is thought to be the same person as GDR, the name inscribed on a bronze wand or sceptre that was found in an area near Atsbi and Dar'a/Addi-Galamo in northern Ethiopia.

GDRT has been equated with the anonymous king of the Monumentum Adulitanum, which would date his reign c. 200 – c. 230. However, the two rulers are usually thought to be distinct. However the French scholar Christian Robin, studying the inscriptions at al-Mis`al in Yemen, has shown that GDRT, and his successor `DBH, lived in the earlier half of the 3rd century.

GDRT is first mentioned in South Arabian inscriptions as an ally of `Alhan Nahfan, king of Saba, in an inscription at Maḥram Bilqīs, at Ma'rib in Yemen, the temple of the moon god Almaqah /Ilmuqah.[8] According to Stuart Munro-Hay, the inscription reads

they agreed together that their war and their peace should be in unison, against anyone that might rise up against them, and that in safety and in security there should be allied together Salhen and Zararan and `Alhan and Gadarat.
Alexander Sima translates the text slightly differently, specifying that it was GDRT who "sent a diplomatic mission to [`Ahlan] in order to form an alliance." Both interpret "Zararan" or "Zrrn" as the name of the palace in Aksum at the time, parallel to "Sahlen," the palace of Saba in Marib. This Sahlen-Saba parallel, along with the Dhu-Raydan-Ḥimyar parallel, was often used by Aksumite kings in their inscriptions enumerating the territories under their control. A Ḥimyarite inscription confirms the Sabaean text, mentioning that Aksum, Saba', Ḥaḑramawt, and Qatabān were all allied against Ḥimyar. `Alhan Nafhan's son Sha`ir Awtar or Sha`irum Awtar later abandoned the alliance with GDRT after he became king of Saba'.[However, during the first part of Sha`ir Awtar's reign, the two powers seem to have joined in an alliance once again, this time against Ḥaḑramawt. Saba's invasion of Ḥaḑramawt with Aksumite help culminated in the latter's defeat and the occupation of its capital, Shabwah, in 225. Sha`ir Awtar's attack represented a major shift in policy as, before the attack, the king of Ḥaḑramawt, Il`azz Yalut, was married to his sister; he had even helped suppress a revolt against Il`azz Yalut.

Although Saba' was previously allied with Aksum against Ḥimyar, both Ḥimyarite and Sabaean troops were used in the attack against Ḥaḑramawt. Immediately following the conquest of Hadramaut, Sha`ir Awtar allied with Ḥimyar against his former ally GDRT. A second Sabaean inscription from the sanctuary 'Awam in Marib during the reign of Sha`ir Awtar's successor, Luha`atht Yarhum, describes events in the latter part of his predecessor's reign. The inscription tells of a diplomatic mission sent by Sha`ir Awtar to GDRT, the results of which are unknown; however, the text later goes on to describe a war between Saba' and Aksum in the southern highlands of Yemen, implying that the negotiations were futile. Aksum lost a battle as a result of the Saba'-Ḥimyar alliance, allowing the South Arabian forces to expel GDRT's son BYGT and his forces from the Ḥimyarite capital Zafar, which had previously been held by Aksum after the Aksum-Ḥaḑramawt-Qatabān-Saba' alliance. Despite this loss, Aksum still held territory in South Arabia, as evidenced by inscriptions of Luha`atht Yarhum (r. c. 230), which detail at least one known clash with hbšt troops in Yemen after GDRT's reign.[9] Peace may have been established after GDRT's death, but war and Aksumite involvement was renewed under his successors such as `DBH and GRMT, and the whole 3rd century was to be dominated by Ethio-Yemeni conflicts