You likely have an indelible image of Superman etched in your brain. But from the moment of his birth (as the offspring of two teenage proto-nerds) in 1938, the Man of Steel has proven far more changeable than anyone expected. While he hasn't aged a day, his appearance, powers, vulnerabilities, and persona have evolved in numerous ways.

In Superman: The Unauthorized Biography, NPR's resident comic book expert, Glen Weldon, tells the life story of the world's first, and still the most popular, superhero, from his creation to the present. He reveals how this cultural icon has been continuously transformed, not just by time but by his travels through a variety of media, including comic books, radio, television, movies, and graphic novels.

The original Superman, a tough-talking, two-fisted bruiser, was quick with a smirk and a sarcastic quip. He was impatient and prone to violence—our hotheaded, protective big brother. Yet that early Superman was a social reformer with a decidedly anti-militaristic streak. Only a few years later, he would become a super-patriot, championing the war effort in comic books and on the radio.

Most baby boomers met "The Big Blue Boy Scout" for the first time not through comics or radio, but as played on television by actor George Reeves. Reeves' Superman was more fatherly than his comic book counterpart, a quality that promptly leached into the comics as well. Weldon documents how Superman's persona shifted again in the 1960s and early 1970s as his middle-aged writers started chasing the nation's emergent "youth culture," unintentionally turning him into our bemused, out-of-touch uncle. Then Christopher Reeve came along to make him a more dashing, good-humored, and sometimes passionate hero.

No biography of Superman would be complete without a thorough treatment of Clark Kent, along with his coworkers Lois Lane and Jimmy Olsen and their boss, Perry White. Weldon tracks their first appearances and development throughout the series and also pays special attention to Superman's archenemy, Lex Luthor.

Complete with thorough accounts of the Man of Steel's more recent films and television shows as well as comics, graphic novels, and a Broadway musical, Superman: The Unauthorized Biography is the ultimate resource for anyone, young, old, or in between, who wants to know everything about everyone's favorite superhero.