Cellen's credits include: the West End revival of CHESS (London Coliseum), SCHOOL OF ROCK (New London), AMERICAN IDIOT (Arts Theatre & UK Tour), JESUS CHRIST SUPER STAR (UK Tour) and DOGFIGHT (Southwark Playhouse).

Cellen could recently be seen in BROMANCE at The Other Palace, and is currently playing the lead role of Olly in the National Tour of CLUB TROPICANA.