Captain Red

OMG.. the poisonous slugs in Keen4 *grins*

Let's see... geemers, squeepts, dragons, moheeks, halzyns, gravitts, yawning maws, automs, shaktools, gawrons, tatoris, shriks, mellows, puyos, scisers, violas, TPOs, choot leechs, homoads, senjoos, yards, autrack, meboids, zebs, sidehoppers, funes, zeebos, gerutas, wavers, drivels, needlers, proboscums, namihes, pemaws, giant sidehoppers, dessgeegas, beetoms, gunzoos, zeelas, power orbs, pincerflies, rios, arachnuses, skreeks, oums, yumees, alcoons, autoads, flitts, space pirates, zeros, rippers, holtz, octrolls, magdollites, owtchs, powamps, metarees, seerooks, ramulkens, zoas, mochtroids, mellas, gulluggs, skulteras, gamets, multiviolas, boyons, sovas, trippers, glowflies, kagos, kobens, skorps, geegas, trilobites, evirs, mumbos, cacatacs, firefleas, septoggs, yumbos, blob throwers, buls, ki hunters, skrees, wallfires, motos, Botwoon, Spore Spawn, Crocomire, Ridley, Kraid, Draygon, the X-bosses, metroids and Mother Brain from the Metroid games.

Definitely the Boreworm and the teddy bear bosses from Splatterhouse 3. I also like some bosses from Symphony of the Night, like Beezelbub and Granfaloon.