Compromised Bitcoin clients? Are there any known cases of compromised Bitcoin clients (whether proprietary or free)?

I don’t mean separate malware that attacks installed clients, but malware that is included in the client itself.

The authors could have included malware intentionally, or unintentionally (without understanding the consequences, e.g. by accepting a code commit of someone else), or their download server could have been compromised, or something else.
There are, but I can't remember where I read about them. Sorry.
There has popped up Litecoin wallets with malware/trojans in them... Therefor there is always a warning/saying that tells you to download the wallet ONLY FROM the official site. (for instance http://litecoin.org)