The character was played by Chris Barrie.
His character traits include anal-retentive adherence to protocol, rank cowardice and inflated ego (for example, The Rimmer Experience). This is reflected in his name, allegedly derived from the practice of Rimming.
He also has an alternate universe counterpart, Ace Rimmer who is a dashing, babe-magnet stud-muffin nonchalant hero -- the exact opposite. Ace Rimmer's total personality difference to Arnold Rimmer boils down to being kept back a year in school. Ace was kept back, and learnt to fight back and stand up for himself, while Arnold was passed through and never learnt how.