Donovan was a mercenary in the same band as Guts and Gambino.

~!He took an interest in the young Guts and offered Gambino three silver coins to have him for the night, unbeknownst to Guts. When night came, Donovan went into Guts' tent and after a small struggle, forced himself onto the boy while telling him that Gambino was the one who prostituted him. After that night, he is murdered by Guts, who followed him to a secluded spot during a battle.!~

His name is Guts, the Black Swordsman, a feared warrior spoken of only in whispers. Bearer of a gigantic sword, an iron hand, and the scars of countless battles and tortures, his flesh is also indelibly marked with The Brand, an unholy symbol that draws the forces of darkness to him and dooms him as their sacrifice. But Guts won't take his fate lying down; he'll cut a crimson swath of carnage through the ranks of the damned—and anyone else foolish enough to oppose him! Accompanied by Puck the Elf, more an annoyance than a companion, Guts relentlessly follows a dark, bloodstained path that leads only to death...or vengeance. 
 
(Source: Dark Horse) 
 
Notes: 
- Volumes 1-5 contain the 16 prequel chapters 0A - 0P. 
- <a href="https://anilist.co/manga/95821/">Chapter 83</a> was omitted from Volume 13 due to the author’s request. 
- Volume 14 includes “<a href="https://anilist.co/manga/36408/">Berserk: The Prototype</a>”. 
- Due to the author's passing, starting from Chapter 365, the manga is illustrated by Studio Gaga (Miura's assistants) and supervised by Kouji Mori (a close friend of Miura's).

Kentaro Miura's legendary series returns in Berserk: The Golden Age Arc - Memorial Edition. 

The lone mercenary Guts travels a land where a century-old war is raging. His ferocity and skill in battle attract the attention of Griffith, the leader of a group of mercenaries called the Band of the Hawk. Guts becomes Griffith’s closest ally and confidant, but despite all their victories, Guts begins to question why he fights for another man’s dream of ruling his own kingdom. Unknown to Guts, Griffith’s unyielding ambition is about to bestow a horrible fate on them both. 
(Source: Crunchyroll, Viz Media) 
Note: This is a TV broadcast of the Golden Age film trilogy, with hundreds of new cuts including the "Bonfire of Dreams" scene and new music by Susumu Hirasawa and Shiro Sagisu.