Gemellus may refer to:
Tiberius Julius Caesar Nero Gemellus (19–37 AD), son of Drusus Julius Caesar and adopted son of Caligula; Tiberius Claudius Caesar Germanicus Gemellus (19–23 AD), twin brother of the previous, died as an infant; St. Gemellus of Ancyra (d. 362 AD), Christian martyr; Gemellus, a pen-name of Voltaire
Muscles Superior gemellus muscle, a muscle in the human body; Inferior gemellus muscle, a muscle in the human body.