Springheel Jak, a legendary thief, lived and reigned roughly 300 years before the Hero's career in Oblivion. His name first appears in a mission assignment from the Gray Fox, a supposedly immortal and infamous Guildmaster of the Thieves Guild.
During the aforementioned mission, the Hero must infiltrate the final resting place of Springheel Jak in search of his legendary boots, which were buried with his body 300 years ago.
Upon opening his tomb, the Hero finds that there are no such boots, but there is a diary. The diary of Springheel Jack has five entries written by the postmortem Springheel Jak. These entries document his transformation when he contracted vampirism and multiple entries detailing his rediscoveries of said diary. These entries show his progressive gain of control over his thirst for blood.
"What do you want? I'll do anything you ask!"
- Springheel Jak's tomb "Take everything, just spare me!"
- Just answer my question! "The family crypts are under the house. They give me the creeps. I have the key. Take it. Just don't hurt me!"
"I'm... I'm still alive!"
If approached again:
"Please don't hurt me!"
- His assumed name (Jakben Imbel) is a play on words of Jack Be Nimble.
- Springheel Jak is clearly a reference to Spring-heeled Jack, a mysterious criminal from Victorian Era England who was said to be able to jump higher than fifteen feet.