Didn't Tex Avery do a lot of the voices in his cartoons?

Not as many as is generally believed.  Tex was a lovely, funny man and he would talk for hours about his work and animation history.  His memory was pretty good and he was very honest so pretty much everything he said seems to have been true…

…except in one area.  Tex said he had done certain voices in his films and he would sometimes replicate his performances for eager questioners, myself included.  He used to tell people that he did Droopy whenever Bill Thompson, who originated the voice, was away. He may have done a line or two here or there but the main stand-by for ol' Droopy was Don Messick. Tex also probably did not do the voice of Meathead in Screwball Squirrel, as I heard him once tell an audience.

In Meatless Flyday, a Warner Brothers cartoon made several years after Tex left the studio, the lead character sounds a lot like Tex, and he told several of us that he'd done it as a favor to Friz Freleng.  It is possible that Tex did go back to WB and record the role…but in the finished film, the voice in question is that of Cy Kendall, a prominent radio actor of the day.

But Tex did do voices in his films.  For instance, he did the evil bulldog in Bad Luck Blackie.  He did the voices that came out of the bottle in Ham-Ateur Night.  He played Dishonest Dan in Homesteader Droopy. He was heard as at least one of the bugs that screamed "RAID!" in the animated commercials for Raid insecticide.  There were a number of others — often snickering or laughing.

The face that he claimed a few other credits probably stems from the fact that he would act out the material when it was discussed in the office, and would often have a very firm idea of how he wanted a given character to sound.  But when it came time to record the soundtrack, there was really no reason not to engage a professional.  Some terrific voice actors were available, they didn't cost much, and Tex would not have received credit or extra money for playing a part himself.

It was also probably more important to have him listening to and directing the performance than to have him giving it.  Certainly, in some cases, what the actors were doing was imitating — to at least some extent — a voice that Tex performed for them.  And perhaps in one cartoon or another, an extra line had to be recorded later and Tex supplied it for a character that was otherwise performed by someone else.

So it's easy to see why he might have remembered doing the voice of a given character in some cartoon.  But he didn't do it as often as he recalled.