Ubuntu

1st Logo (2004-2009)
Logo: On a black background, there is a circle made up of curves with circles in the middle, jutting into the curves, making it represent a group of people holding hands (albeit, very abstract). The circle is also in red, orange, and yellow. To the right is "ubuntu" in a bloated font which is black with a white outline that appears to be glowing. On the bottom is a bar that slowly fills up with orange blocks.

Variants: In different updates, the boot screen will change to look more detailed. Beginning with version 6.10, the bar looks like the Windows XP boot screen bar.

FX/SFX: The download bar only.

Music/Sounds: There are 2 versions:
 * Startup before 6.10: A rising synth with various dings. Sounds somewhat like the 1st half of the PS1 startup.
 * Shutdown before 6.10: The same thing but shortened and in reverse.
 * Startup after 6.10: A tune that sounds like a high and low tom beat with a large violin melody, ending with a cymbal hit and a wildlife sound.
 * Shutdown after 6.10: The last note of the violin melody from the startup sound.

Availability: Extremely rare.

2nd Logo (2009-2010)
Logo: Very similar to the last one, except it is in a brown background with a shade. The logo is colored white as well as the download bar, which is thinner.

FX/SFX: The download bar only.

Music/Sounds: Same as the startups and shutdowns after 6.10.

Availability: Same as above.

3rd Logo (2010-2019)
Logo: Similar to the last one, but the background is dark maroon, the text "ubuntu" is in a different font and the icon is moved to the top right of the text and put in a circle. Also, the download bar looks like white circles turning orange after 0.75 seconds, reversing after that and looping.

FX/SFX: The download bar only.

Music/Sounds: Same as the startups and shutdowns after 6.10. In 18.10, there isn't a shutdown sound. Also, the startup sound is changed; it starts with a reverse cymbal, and then a 4-note xylophone melody is played, with the final note being long.

Availability: Same as above.

4th Logo (2019-)
Logo: Same as before, but the logo is put to the bottom, the background is black and the download bar looks like a spinning half circle.

Variant: Beginning with 22.04 LTS, the logo has changed, so the curves of the circle are merged, and the circle becomes a vertical rectangle. The text is now title case and is at the right of the rectangle.

FX/SFX: The download bar only.

Music/Sounds: Same as the startup in 18.10.

Availability: Same as above.