John Altoon: Untitled, 1964, ink, pastel and airbrush on illustration board, lettering by Ed Ruscha, 60 by 40 inches; at LACMA.

John Altoon (1925-1969) has long been beloved by a cult audience for his gorgeous and quirky abstractions, outrageous psychosexual drawings and legendary manic personality. Following on a slightly larger 1997 retrospective at the Museum of Contemporary Art San Diego, this tighter, more elegant survey, curated by Carol Eliel for the Los Angeles County Museum of Art and the Rose Art Museum in Waltham, Mass. (where it opens Oct. 8), presents the artist as a quintessential L.A. iconoclast. Laudatory quotes from various contemporary artists were plastered on the walls at LACMA, but special pleading isn't needed for work that feels so fresh.

The Gorky-like abstract forms of Altoon's mature paintings ooze with an impudent sexuality. Using moody melds of purple, maroon and lime in shapes evoking mystery cast-off organs from classroom dissections, Altoon demonstrated the power of organic abstraction to tap our mixed reactions to the physical body. Both seductive and repulsive, Altoon's amoebas and creepy critters engage in coital battles beyond gender. In four paintings from 1962 (all works untitled), weird winged creatures vie with what look like penis-shaped turkey bones, disembodied breast-shapes, a red caterpillar and green slugs.

In slightly later works (1964) on illustration board, puffs of airbrushed pastel colors highlight forms set against white backgrounds, adding a quirky decorative element to compositions that seem battlegrounds of the psyche. In one, in ink and airbrush, Altoon forms a shape that mordantly resembles a bishop's mitre from a pair of billowy female thighs, with a crucifix emblem at crotch level. This he places to the left of a kind of giant floating shrimp.

In fact, sex for Altoon represented a sort of religion, awe-inspiring, desired and feared. Hardly the result of a carefree libertinism, Altoon's drawings sprung from psychoanalytic sessions in which he explored the dark side of sexuality. Dubbed by Walter Hopps "the fastest line in the West," Altoon was a facile draftsman able to produce up to 30 ink-and-watercolor sketches in an afternoon, all executed with virtuosic brio. Witty 30-by-40-inch knock-offs depict jaw-droppingly perverse and anxious narratives. In one, a despondent, disembodied penis on roller skates offers a bouquet to an equally despondent nude woman; in another, a penis bursts out of a jar of Smucker's jam; in still another, a buxom nude woman with a hound's head beats an older man whose body is that of a mangy cur. For sheer poetic strangeness, sexy charm and outright beauty, Altoon's drawings trump those of today's bad boys Raymond Pettibon, Carroll Dunham and Paul McCarthy.

For much of Altoon's career, commercial gigs paid the rent. He avenged his Mad Men jobs with advertising satires—parodic layout paintings and drawings complete with product logos (several with lettering done by Ed Ruscha). A work from 1962-63 literalizes the seductive appeal of an ad for White Owl cigars, portraying a dude lighting up next to his golden girl, both nude from the waist down, genitals displayed. Other sardonic takes on Christian Dior, Bell Telephone and Colgate toothpaste comically reveal what we all know: sex sells.

More startling is an untitled 1964 parody of an actual Life magazine cover featuring Lee Harvey Oswald. In Altoon's bizarre, 5-foot-high ink, pastel and airbrush sketch, he depicts Oswald holding a cluster of flags from various nations along with the shotgun used to kill Kennedy. Next to him, a muscled Tarzan bends the muzzle of the gun with his bare hands. A caption reads: "Tarzan and I were watering the lawn the day it happened. Especially for LIFE by Lee Oswald." The drawing is perhaps a biting commentary on the media circus generated by the JFK assassination, rivaling in vitriol Bruce Conner's bitterly intense film Report (1967). Altoon's works are comical and disturbing, crucial documents of their time that remain relevant to a host of later themes and ideas.