I find it interesting that the cover features Bron as one of the characters that are shown. I think that's the first time an adult has ever been on the cover of a LBT movie, though I'm not totally sure. I don't have the old movies anymore and the covers have changed since I re-purchased them.
Well, if you want to count the villains as adults, you have:
Sharptooth on the original LBT movie.
Chomper's Dad, Ozzy and Strut on LBT 2 VHS.
Icky and Dil on LBT 4 VHS.
The Shark on LBT 5 VHS.
Many Adult Longnecks on LBT 10 DVD.
And now we have Bron on the Friends Forever DVD of the TV Series.
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Hm, counting them all, that's about a third right there.