Alexander "Alex" Olsen was a brilliant young scientist who lived during the early years of the 20th century. As a young man, he met and fell in love with a woman named Linda. The two soon wed, but their marriage would last barely a year before tragedy was set to befall them. 
Alex's assistant, Damian Ridge had secretly pined for Linda's affections. Although Alex was his best friend, he could not abide watching him living in bliss with the woman he secretly adored.
In 1905, Damian waited until Alex had gone to bed, and then crept down into the laboratory to tamper with his experiments. He altered some of the chemical solutions in the lab and waited for Alex to resume his work. The following evening when Alex attempted to complete his projects, the unstable chemicals exploded nearly killing him in the process. Damian dragged Alex's body out of the house and dumped it into the nearby swamp where he left him for dead. With Alex out of the way, Damian now mustered the courage to pursue Linda. 
Damian never told Linda the truth concerning his involvement in Alex's demise, but he took advantage of her suffering and played the part of the concerned friend. In time, Linda fell in love with Damian and the two were married.
As time passed, Damian began to believe that Linda suspected his complicity in her ex-husband's death. Linda knew that Damian was a man of many secrets, but could never allow herself to think that he could actually murder another human being – let alone his best friend. Damian could no longer endure his growing suspicion however. Although he loved her dearly, he was prepared to end Linda's life if it meant keeping his secret safe.
What neither Damian nor Linda realized though was that Alex Olsen never truly died. His chemically bathed body reacted with the vegetation of the nearby swamplands, transforming him into a shambling, muck-encrusted Swamp Thing. Unable to lend voice to the rage growing inside of him, he swore that Damian would pay the price for his betrayal. The Swamp Thing burst through the windows of the Olsen estate and attacked Damian. Easily snapping his neck with his powerful fingers, he let Damian's corpse slide down onto the floor. Linda emerged in the room and began screaming. The Swamp Thing turned towards her, but was unable to tell her that he was in fact her lost husband. Terrified, Linda ran from his presence.
Lost and alone, the Swamp Thing abandoned his past existence, preferring to live in solitude in the swamplands that would become his home. He befriended a group of Cajuns and helped them to understand their relationship with nature. The Cajuns referred to the Swamp Thing as Le Bon Gumbo. The name translating roughly to mean, "the good gumbo man". Called such because while he was present in the swamp all local vegetation flourished, food based crops included. Incidentally, this is a name all future Swamp Things in the Houma, Louisiana region would come to share. 
Around the year 1937, the Alex Olsen Swamp Thing had finally tired of humanity and its growing strife. He was by then more than ready to retire and gradually lose himself in the intertwined shared mind of the Parliament of Trees.  Where he would later encounter his direct successor, Alec Holland, the current Swamp Thing. Conveniently, by that time Alex Olsen claiming to be the only member of the Parliament who could remember how to form words verbally. Though their messages rather cryptic and at that time of little use or comprehension to Holland, oft referring to the "ways of wood". 
- Science: Alex Olsen was a brilliant scientist and maintained his intellect even after the accident that transformed him into the Swamp Thing. However, he no longer possessed the manual dexterity required to handle delicate instruments.
The Swamp Thing's ultimate strength level is unknown, but he has been shown to snap a grown man's neck with little to no effort.
- Although this character was originally introduced during DC's Earth-One era of publication, their existence following the events of the 1985–86 limited series Crisis on Infinite Earths remains intact. However, some elements of the character's Pre-Crisis history may have been altered or removed for Post-Crisis New Earth continuity, and should be considered apocryphal.
- Alex Olsen's first appearance in House of Secrets #92 is often miscredited as the first appearance of Swamp Thing (Alec Holland).
- Although never confirmed, it is likely that Linda Olsen Ridge is a direct ancestor of Linda Holland (whose maiden name was Olsen Ridge). Linda Holland became the wife of scientist, Alec Holland, the future Swamp Thing.
- 11 Appearances of Alexander Olsen (New Earth)
- 5 Images featuring Alexander Olsen (New Earth)
- 6 Quotations by or about Alexander Olsen (New Earth)
- Character Gallery: Alexander Olsen (New Earth)
Swamp Thing and is predominantly seen in the Swamp Thing family of titles. This character may be part of the Swamp Thing's supporting cast, a minor acquaintance, or one of his adversaries. This template will automatically categorize articles that include it into the Swamp Thing Characters category.