Nazdreg Ug Urdgrub
Warlord of the Bad Moonz Clan, Nazdreg Ug Urdgrub is one of the wealthiest Orks to ever antagonize the Imperium, and quite possibly the richest Ork alive in 40K. Described as being incredibly cunning and more concerned with wealth than war, Nazdreg is what every Bad Moon aspires to be and more.
Nazdreg is also a part-time collaborator with Ghazghkull Mag Uruk Thraka, having worked with him to develop the "Tellyporta" that would be used to great effect on Piscina IV and later on Armageddon, the Third War of which Nazdreg also participated in. Nazdreg could be seen as the Mork to Ghazghull's Gork, where major Ork warlords are concerned.
After Armageddon, the only major campaign Nazdreg took part in was on Medusa V, in which he lost the war and his personal Space Hulk Ognazdreg Gargdurslagulk. But, he snagged an Imperial Battleship for his troubles. Since his escape, he remains at large.
Nazdreg embodies traits that aren't common in most modern depictions of Orks: an obsession with something that isn't war, the ability to weigh risks and options, a sense of when it's time to run and hide. That's probably why he doesn't show up much in the lore or on the table. He's also described as being overweight, which is less common for Orks than the gut-forward posture of their models would lead you to believe.
Tabletop
Nazdreg has made some sporadic appearances on the tabletop, appearing in the Second, Third and Seventh editions of the codex. He is always depicted wearing a set of Mega Armour, wielding a Power Claw and his Kustom Blast-X - a large plasma weapon with considerable ranged accuracy. He also allowed you to take extra Heavy Support choices, back when that mattered.