Catrum was an ancient city and diocese in Africa Proconsulare. It is now a Roman Catholic titular see.
Catrum was among the numerous cities in the Roman province of Mauritania Caesariensis which were important enough to become suffragan dioceses, but faded (plausibly at the 7th century advent of Islam) - in its case so completely that even its location in present Algeria is unclear. No bishop was historically documented.
The diocese was nominally restored in 1989 as Latin Titular bishopric of Catrum (Latin) / Catro (Curiate Italian) / Catrensis (Latin adjective).
It has had the following incumbents, so far of the fitting Episcopal (lowest) rank :