Kudryavka Laika:

A quick bark for Laika or "little barker" in Russian, who was launched into space on Sputnik 2 on this day in 1957. The technical feat was that this second sputnik was six times heavier than Sputnik 1, and was less than one month later -- a fact not lost on the U.S. rocket effort.

Here she is:

What is little known is that this launch was done by Korolev as a response to a special request by Khruschev to "do something special for the upcoming anniversary of the Revolution." ...and that there was no way down for the scrappy little Moscow street dog, who lived up to her name, forlornly barking until her oxygen ran out two days later. Sniff.

(A later note: documents released only lately have revealed that Laika died within hours of launch because the cooling system failed. I also found out that she was sealed in the capsule four days before launch! Poor girl.)