Abu Thabit 'Amir ibn Yusuf (Arabic: أبو ثابت عامر) (1284 – 28 July 1308) was a Marinid ruler of Morocco for around a year.
The Marinid sultan Abu Yaqub Yusuf was in the Kingdom of Tlemcen laying siege to the Abd al-Wadid capital when he was assassinated.
During this long siege, which had been in place since 1299, the Marinid sultan was unable to prevent a Nasrid-sponsored pretender Uthman ibn Abi al-Ula from landing in Ceuta in 1306 and seizing much of northern Morocco.
The new Marinid sultan Abu Thabit, whose ascendancy was contested by four pretenders, had to choose between pressing the siege or recovering his dominions.
Abu Thabit rushed his troops back to Morocco to take on the fourth pretender, Uthman, leaving little or no garrisons to hold the Marinid positions in his wake.