Arthur Nicolas R. Theate (born 25 May 2000) is a Belgian professional footballer who plays as a centre-back or left-back for Bundesliga club Eintracht Frankfurt and the Belgium national team.

Theate played youth football for Alliance Melen-Micheroux, Eupen, Genk and Standard Liège.

At Genk, he was repositioned as a left winger after the arrival of a new player, after which he moved to the position of left-back and then centre-back.

[5] In the summer of 2020, Theate saw no prospects of succeeding at Standard Liège, after which he was offered a trial with Belgian First Division A club Oostende.

On 4 October 2020, he scored his first professional goal, heading home a cross against Royal Excel Mouscron putting his team in a good position ahead of their 3–0 victory.

[13] On 26 August 2021, Theate signed with Serie A club Bologna on initial season-long loan, with a subsequent obligation to buy.

[14] On 18 September 2021, Theate made his Bologna debut against defending champions Inter Milan on the fourth matchday of the season.

[22] He also scored in his European debut with a strike from distance against AEK Larnaca in the UEFA Europa League group stage, as Rennes won the game 2–1.

[30] He was selected for national coach Roberto Martínez's squad ahead of the 2022 FIFA World Cup,[31] but failed to make an appearance as the Red Devils were knocked out of the tournament at the group stages for the first time since 1998.