Rimuru Tempest

Race: Human (past life) → Slime → Demon Slime
Age: 37 (past life) → 2 (anime/manga), 3 (light novel)
Sex: male (past life) → Sexless
Title: Ruler of Monsters, Jura-Tempest Federation Chancellor,
Divine protection: Storm Crest
Magic: Element Magic archive, Spirit Magic archive, Greater Spirit summoning, Greater Demon summoning,
Ability:
Species Skill - Universal Sense, Universal Thread, Universal Shapeshift, Infinite Regeneration, Demon Lord Haki, Enhanced Replication
Ultimate Skill - Wisdom King Raphael, King of Gluttony Beelzebuth, Covenant King Uriel, Storm King Veldora,
Resistance: Physical Attack Nullification, Natural Effects Nullification, Abnormal Condition Nullification, Spiritual/Mental Attack Resistance, Holy-Demonic Attack Resistance

The main protagonist of the series and Founder as well as Chancellor and King of the monster nation known as the Jura-Tempest Federation. Originally Mikami Satoru, a 37-year-old general contractor, he was stabbed by a passing robber while protecting one of his co-workers and reincarnated in a new world as a slime, one of the lowest monsters on the food chain.

In spite of the situations he finds himself in, he often tends to be very easygoing, yet calculating and cautious. A pacifist at heart, he tries to avoid casualties and save people if possible and wishes to maintain good relations with humans.

(Source: Tensei Shitara Slime Datta Ken Wiki, edited)