Infected Leaders are boss zombies if you like and these can only be obtained by attacking Infected city's (only one leader spawns in every city, so I've heard) purchasing Infected leader containers, or you can obtain them in the Casino.
Since there ain't anywhere that tells, or even has pictures of the Infected leaders. I shall tell you the names of the Leaders I know.
City Boosts: +20% Infantry Defense +20% Vehicle Defense
March Boosts: +20% Vehicle Attack +20% Infantry Attack
Duration: 30 Minutes
City Boosts: +25 Infected Defense
March Boosts: +20% Infected Defense +20% Infected Attack
Surgeon Deathwing or darkwing (infected crow)
Tyrant II :+40% Gather Speed, +30% Troop Attack
Gorbo the Destroyer II : +200% Infected Attack
Undying I : +30% Infected Attack
Blue Steel V
City Boosts: +10,000 Troop Training Limit and +50% Training Speed
March Boost: +150% Marching Speed and + 200% Vehicle Attack
That's all I know and have so far, once I find out about more leaders, I'll update this topic :)
also feel free to add to the list and the Infected leader's stats :)