From Homestar Runner Wiki
Like ducks, goats and snakes, lions are one of the few real animals that are constantly mentioned in the Homestar Runner universe.
- Debut: Email studying — The Bookazon.com Easter egg includes a review for Leomard Sportsinterviews' book This Book is Better Than 1st, 2nd, and Quite Possibly Even 3rd Base that reads "Lem has come roaring back like some type of book writing lion."
- Teen Girl Squad Issue 6 — The "Gift Exchange Lion" (who appears to be missing a leg) is the lion that Cheerleader, So and So, and The Ugly One all dive into in pursuit of Decemberween presents. It has a half digested gazelle carcass within it.
- Experimental Film — A Powered by The Cheat lion appears on the screen of an ATM, wearing Homestar's hat and a caption reading "it's a lion!" Later, a crowd in grandstands holds up cards forming the same message.
- Figure Eight — In the end of the video The Brothers Chaps made for They Might Be Giants there is a book with "it's a lion!" written in it. 
- Because, It's Midnite — "Heart of a lion" is a repeated line from Limozeen's "Because It's Midnite".
- Email secret recipes — Strong Bad says that the senders of the email, being from Nigeria, are probably used to eating "exotic fruits, nectars and...lions".