Traditional heavy metal, also known as classic metal or simply heavy metal, is the seminal genre of heavy metal music before the genre "evolved and splintered into many different styles and subgenres."

The traditional heavy metal sound is often similar to that of hard rock, and, as noted above, some authors even consider the two genres as synonymous. However, others such as Paul Dunoyer, although recognizing many similarities between both genres, considers that heavy metal tends to depart from the original blues roots of hard-rock. A view also shared by Garry Sharpe Young. According to this view, original heavy metal is characterized by mid-to-fast-tempo riffs, by thumping basslines, crunchy riffs, extended lead guitar solos, and clean, often high-pitched vocals and anthemic choruses. One of the most important and innovative concepts of traditional heavy metal was the use of the double lead guitar pioneered by bands like Scorpions and Judas Priest. And although, this concept was sparingly used by earlier hard rock bands like Uriah Heep and UFO, it was wholly developed as a heavy metal element during the traditional heavy metal era. This concept of dual lead guitars would reach more profound heights during the late 1980s when other bands like Accept would also use it. Another musical concept that was developed was galloping rhythmic patterns which were extensively used in Iron Maiden songs, but also in certain Accept's songs ("Restless and Wild", "Metal Heart"), as well as Judas Priest ("Diamonds & Rust"), Dio ("Holy Diver"), Aria ("Geroy Asfalta", "Krov za Krov") or Trust ("Varsovie/Uptown Martyrs").

Traditional heavy metal is lyrically diverse, with a wide variety of themes. These include: the occult, party and fun, fantasy, social themes, drug themes, life on the road, and war themes. A single band can write songs based on various themes. For instance, Judas Priest writes songs on party (Living After Midnight), social themes (Victim of Changes, Breaking the law), love songs (Prisoner of Your Eyes) and fantasy/fiction (Painkiller). Some bands may exclusively write about party, sex, love and drugs, while other bands (such as Iron Maiden) have war, history, culture, violence, fantasy and religion as recurring themes. War, horror fiction, mythological and historical topics are frequent themes though. Songs may also be anthems to heavy metal music itself, for example the songs "Heavy Metal" by Judas Priest, "Heavy Metal is the Law" by Helloween, "The Gods Made Heavy Metal" by Manowar, and "Slaves to Metal" by Accept. War is a frequent theme. Some bands including Manowar and HammerFall tend to deal with it in a romanticized way, praising courage and masculinity, while other bands including Accept ("Russian Roulette", "Man Enough to Cry", "Walking in the Shadow"), Black Sabbath ("War Pigs") and Iron Maiden ("Afraid to Shoot Strangers", "2 Minutes to Midnight", "The Trooper") rather deal with war in a more serious and critical approach. Horror and mysticism sometimes overlap with religious topics, like the Apocalypse.